How to Recover a Crashed Windows PC
Created | Updated Jun 1, 2009
What should you do if your PC crashes badly and won't restart? This is for people who know what they are doing. If you are a novice, do not attempt any of this, you may make the problem worse1.
Novices to computer repair should follow these rules:
Keep your cool. It may not be as bad as it seems.
Don't fiddle with anything you don't understand.
Call your technical support number or your knowledgeable computer nerd friend.
If the computer won't start up, turn it off.
If the computer is asking you for a decision, do not turn it off. Also, don't guess at the answer.
Always read everything on the screen, especially if being asked a Yes/No or Yes/No/Cancel question.
The following are steps for computer expert/professionals only. The author denies any responsibility for any damage caused to your computer(s) from following this advice, particularly if you are really a novice pretending to be an expert. You may also want to print out this entry, as it may be difficult to view it if your computer goes faulty.
Most people will say 'Don't Panic'. It's certainly the motto of h2g2. In this situation, it is wrong.
Panic. Leave the room and have a good panic, you'll probably develop a cold sweat. Do not return to the computer until it has passed. Find a cold tap and splash lots of water on your face. Repeat the mantra: 'It's only a computer, it's only a computer, it's only a computer'. Take lots of slow, deep breaths. If you can find someone, have a good rant with them.
Assess the damage. Try to figure out how long this is going to take to fix. If it will require several hours of work and it's late at night, leave it for the morning. Never work on recovering a computer when you're tired.
In particular, you'll need to find what you did to cause the crash. Was it a new piece of software being installed? A new piece of hardware?
Types of Crash
Windows Protection Error
No-one wants to see this fault. It is usually caused by virtual device driver (VxD) conflicts. Some are recoverable and will let Windows continue to load. Others are not. If the computer can be started in safe mode, it may be possible to remove the VxD. Alternatively, you can start the computer in step-by-step mode and try to load the VxDs one at a time to see which one causes the problem.
The protection errors that freeze the computer on each restart may need the operating system re-installed. This isn't as bad as it sounds and can have a few benefits2.
Microsoft's How to Troubleshoot Windows Protection Error Messages is very helpful.
Computer Freezes When Loading Desktop
This can be caused by an application in the start up3 crashing while trying to load. Reset the computer and hold the [Ctrl] button down as the computer starts Windows. This will bypass most of the start up programs, which may solve the problem.
On some operating systems, Windows NT for example, it is possible to turn off the service that communicates with the keyboard and mouse. The author has done this not once, but twice.
Computer Will Not Turn On
If the computer won't turn on at all, check the obvious things:
Is it plugged in, are the leads connected?
Is there power in the house4?
Check the fuse. It's the most likely point of failure.
Check the surge protector on the computer's power strip5.
Is the power switch pressed in fully?
Have you heard a loud bang recently? This could be the wires inside the insulation fusing and snapping6.
The next step is to try to find out how far the computer is getting. Is the hard drive turning on? How about the fans? If part of the computer is getting power, the internal power cables may have worked loose. If not, the PSU7 may be faulty. It's relatively cheap to buy a new one and they are all fairly standard but, unfortunately, on some computers it can be difficult to remove the old one and install a new one - it's basically the first thing screwed to the frame when the computer is being built, so almost everything else has to come out first.
Computer Continually Resets
This can be caused by several things.
A power supply fault.
A bad line in the autoexec.bat file.
Loose connections (between the graphics card and motherboard, for instance)
BIOS fault protection. The CPU may be overheating, or some other fatal error may have occurred.
The power supply will probably be a faulty PSU or loose/faulty connection cables. Don't forget most motherboards have two power connectors attached to them; if one is loose or faulty, it can cause some very odd faults.
Check the config.sys and autoexec.bat for errors. A real fault was caused by the following command sequence:
If you would like to test your skill, the answer is here:8.
Computer Crashes Just After Loading Windows
This can be caused by almost anything. The more applications starting up, the worse the de-bugging process can be. Again, holding the [Ctrl] button while Windows loads can help determine what is causing the crash. A virus is a distinct possibility, but don't panic and explore all options.
Computer Just Beeps When Turned On
These are probably BIOS beep error codes. There are several and all mean different things. There's supposed to be one short beep on start up. One long beep means something directly attached to the motherboard is missing (memory, processor and video card). Try re-seating them.
How to fix it.
The equipment falls into two categories: hardware and software.
- Screwdriver (non-magnetic)
- Volt meter
- Anti-static guard
- Can of compressed air (hand-held size)
- Fuse tester
System boot disk
Anti-virus recovery disk set
Original Windows installation CD and boot disk
Ghost image of the hard drive (if you have one)
Wintop (or other Windows NT Task Manager-like application)
Startup Program Manager (for all those hidden start up programs)
Most problems will fall into the software problem category, so these will be dealt with first.
These are usually the easiest to fix, which is a good thing as they are the most common. In these days of Windows 98, Me and 2000, config.sys and autoexec.bat errors are rare, but can still occur. Generally they should be backed up regularly, but if you are a typical PC user, you only think about backing up once an error occurs. If you need to remove and replace your files, copy the ones from the Windows install disk. They should get your computer started with CD-ROM support. Soundcards and any other peripherals can then be re-installed along with any software and this should return the config and autoexec to their original state. If you are more experienced, you could edit the files and REM the faulty line(s) out.
If the problem is being caused by a Windows application starting, the best bet is to start in Safe Mode - use the start up program manager and turn off anything you don't recognise as essential. As long as you stay out of the 'System' start up section, you can't cause any real harm. The best manager programs allow you to simply 'un-tick' the applications without deleting them, so you can undo any mistakes. This can often help with applications which crash when trying to load at the same time.
That stuff about letting your computer acclimatise before turning it on for the first time is true; if the computer heats up too fast (when it is turned on), it can cause problems.
Warning: When working inside the PC, always turn the power off, unplug and use an anti-static wrist guard.
The most common hardware problem is seating. This is where a card, memory card or the CPU has become loose and needs to be pushed back into place. The computer normally will not start up and will give one long beep followed by a long gap. The bad seating can also allow dust to get in, so the best idea is to remove the component and spray the area with compressed air to remove any dust (or blow on it) and then re-insert the component. Be careful with the CPU; it is the most delicate part of the computer that can be removed.
Don't forget to check the obvious things. Is the monitor cable plugged in at both ends, for example.
The main rules of internal fault checking are:
- What is getting power?
- And what is getting a data signal?
Firmware is half way between software and hardware. It can be used to describe several things, but most people use it to describe the software settings for the computer's hardware. These use terrifying acronyms like IRQ, DMA and resource range. It's not as confusing as they want you to think.
|IRQ||Interrupt Request. All system resources need a separate IRQ channel to interrupt the CPU from what it is doing and get attention. The system clock has channel 0, keyboard has 1 and mouse has 2. The lower the number, the higher the priority given to any request. Soundcards need an IRQ channel, and most are 'picky' about the channel they want, even the best on the market offer only around three possible channels, the worst ones offer only one channel.|
|DMA||Direct Memory Access. A clever concept. As each bit of hardware needs data from memory, rather than interrupting the CPU, then getting the CPU to get the data for them (an enormously wasteful process), they use their own channel and get the data themselves.|
|Resource Settings||This is simply the range of memory 'cells', addressed in Hexadecimal, that the device is going to be assigned to store any data to share with another device or application, such as the operating system and a soundcard. Like IRQ and DMA, it must have a unique value.|
In these days of 'plug and play', Windows will configure most new hardware, but it isn't infallible and there are plenty of devices that aren't plug and play. Generally, changing the settings is a bad idea, unless there is a hardware conflict that Windows cannot resolve. Despite the advertisement, even Windows NT & 2000 can fail to resolve conflicts. Before changing the settings, right click on 'My Computer', click on the 'Hardware Profiles' tab and make a copy of 'Original Configuration'. That way, if you make a disastrous change, the computer will always ask you which profile to boot in when loading and there's less danger of causing a fault you can't fix without re-installing the operating system. Note the word 'less'.
How to prevent it happening again.
Get yourself a back-up strategy. There are several good methods.
Back-up your operating system to a removable media, like a tape or CD.
Ghost your hard drive onto a CD. This allows you to restore the system quickly.
Partition your hard drive and clone your operating system drive onto it.
Things to Avoid
There are plenty of innocent-looking things in your computer that can cause serious problems if fiddled with. The general rule is: if you don't know what something does, leave it alone.
CONFIG.SYS: This contains information about your system configuration, what hardware is installed, settings, etc. Back up this file to CONFIG.OLD or similar before changing it.
AUTOEXEC.BAT: This contains settings and commands to run. The settings govern hardware, typically CD-ROM drives and soundcards, but also other equipment. The commands to run usually include the command to start Windows and possibly also virus checkers and any other system critical software (like compressed hard drive software). As with CONFIG.SYS, back-up this file to AUTOEXEC.OLD or similar before changing it.
The Registry: Never mess about with the registry unless you know what you're doing. Make a back up before you start. Remember; changes to the registry take effect immediately, you do not save your changes, like in Word. Some parts are resilient, like the parts governing software, but others control the way your computer works and are dangerous to tweak.
Un-installing: Get yourself a proper uninstaller. Although the ones with each new version of Windows are better than their predecessors, they still aren't as good as the professional ones available. They work by simply recording every change the installation makes, then reverses it. You can even view the changes log. Its big advantage is that it makes a distinction between a file created during install and a file that was already there in the computer.
Protection: Don't install software unless you know where it's from and what it does. Get yourself an anti-virus program and keep it up to date with regular updates. Get a firewall program if you go online.
Incompatibility: Don't use utility programs designed for Windows 3.11 on Windows 98. They won't work and can cause a lot of damage.
In general: Always ask yourself 'Is this a good idea?' before doing anything you haven't done before.