My computer started crashing randomly the other week. The screen would turn multicoloured, almost checkered, then go black and i'd have to switch it off for a minute. If i switched it on straight away it'd load but go really really slow.
Anyway, it lasted about a week and then suddenly stopped for a week or two. Then suddenly yesterday it started doin' it again. Did it 3 times, but after the 4th time when i tried to switch it on again it says "Windows could not start because the following file is missing or corrupt: \Windows\System32\Config\System"

then says how to repair it boot from the XP disk and press r on the first screen.

The next problem is it doesn't seem to want to boot using anything but the hard disk. I've changed all the boot options in the BIOS to cd-rom and selected CD-ROM from the boot menu. All i get is "DISK BOOT ERROR". and when i try and boot from floppy disk, it doesn't even attempt to access the floppy disk, just says the same thing.

Could it be my hard disk? I still don't understand why it wont boot from cd or floppy though :-(

Thx for any comments.

Disconnect the harddrive and see if you can get it to boot either to floppy/cd or just into bios.

I used to have a signature but it disappeared and I just couldn't be bothered writing another so please feel free to ingore this.

The most likely thing is your power supply is failing.
- it can be producing inadequate or no 5 volt output.
It is possible for the mboard and hard drive(s)to boot and for you to not have the 5 volts necessary from the power supply for the floppy drive and CD drive, in which case the mboard will not find a functioning floppy or CD drive. If you try the floppy or CD drive in another computer they will work fine.
- it can be producing too much voltage e.g. where it should be producing 5 volts, it may be a lot more than that - voltages that are too high can damage components in a short time. Floppy and CD drive logic boards are often the first to fry - if you try them in another computer they won't work on that computer either.

- a malfunctioning PS can cause random reboots, blue or black screens in Windows, and damage to the data on the hard drive when it does that, video corruption, bizarre video behavior, and/or damage to the video card.

- at first the problems may occur only when the PS has fully warmed up.

How do you tell if the PS is malfunctioning?
The best way is to borrow a known good PS with enough capacity and try it, or try your PS in a working computer.
Make sure all the wire colors and numbers of wires on the main connector from the PS are the same - if they are not one PS is not compatible with the other!
If you can't do that....
take it to a computer repair place and have them try another PS, or.......

Sniff the PS fan outlet area with the power off - a strong burnt wiring / burnt plasticy smell indicates the PS has been overheating or has been malfunctioning, regardless of whether the PS fan is spinning properly.
Try turning the PS fan from the back of the case with a pencil or something slim - it should move in jumps, but be easy to turn - if it is harder to turn, the fan is spinning slower than it should or has stopped spinning, the PS has probably overheated and damaged itself, and the PS is probably in the process of dying.

Look in your bios Setup at the current voltages (if you have the monitoring chipset for that) - +3.3, +5, and +12 volts should be within 10% of nominal values - your Vcc (cpu core voltage(s)) should be within 5% of nominal value(s). Voltages that are too high can do a lot of damage in a short time.
Some recent power supplies have two voltage sources, on separate "rails" - one source may be wonky.
You could also measure the 12 and 5 volts at the power connectors to a drive - red is +5 volts d.c., yellow is +12 volts d.c., black is negative, probably doesn't matter which one.
The PS fan should be spinning at the speed it is supposed to be - some spin according to how warm the PS is, slower when cooler, but it may not have that feature and in that case would spin quite fast. If it spins too slow or has stopped, the PS will overheat and fry itself, malfunction for a while, and eventually die.

Some PS problems only show up intermittantly, or only when you add an additional load to the computer - when the computer is booted, or when you are running something that stresses it more, such as when you are burning a CD or DVD, or playing a recent game.
You could try installing a mboard monitoring utility that can monitor your temps and voltages in Windows, and set it up so that it is monitoring all the time and will warn you if something goes out of whack, particularly the voltages.
.....

Ok well the power supply is still working etc and no burning smell. I've found an old hard disk and reformatted it and installed XP on it using differnet computer. It worked fine in that computer, but when I put it in mine, when XP tries to load I get the BOS, telling me that it had to shut down windows to stop damage to my computer. Does mean it's the motherboard? Or could it be that the power supply isn't supplying enough power.

"Does mean it's the motherboard? Or could it be that the power supply isn't supplying enough power"

It could be either, or the cpu or some other component is damaged, or something else.
Also, if the computer isn't protected from power spikes and surges it could have been damaged from exposure to those.

The most likely is you have a bad PS. Your symptoms all point to that. Sometimes that's hard to confirm.
Have you tried the floppy and cd drives in another computer yet? If they are dead in the other computer it has to be the PS.
Try the last suggestion in response 2.
Try another PS.
My brother had a Antec PS that seemed fine in every test I mentioned - it would reboot when he tried to use his CD burner - it stopped doing that when he tried another PS.

Or you could have bios settings that are wrong or a dead mboard battery and that is why the computer is shutting down. If it goes to the bios and shuts down before windows even loads, your bios settings are wrong, or the mboard battery for the bios on the mboard is dead or too weak and the bios cannot retain the correct settings for your cpu after the computer has been shut down.
If it's bios settings that are causing your problem, you will get the same message even with the hard drive disconnected. In that case, make sure the mboard battery has proper voltage, or just replace it - they're cheap. If the battery is okay, load Defaults in your Bios Setup.

If it get to the point that XP starts to load and you get the message from XP......
When you set up XP on a hard drive on one computer and then install the hard drive on anorther computer that has different hardware, the difference in hardware is too much for XP to handle. You can get various messages because of that, or just a blinking cursor at the top of the screen. I haven't encountered XP giving me a it had to shut down windows to stop damage to my computer message in those circumstances, but I suppose that's possible.
In that case you need to do an XP Repair Setup.
You need a cd drive that works for this of course.
An XP Repair Setup will not harm your existing Windows installation, but it can only fix things Windows detects as wrong, and/or replace corrupted or missing Windows files that are on your original XP CD. If running it doesn't cure enough of your problems and/or the problems are caused by things not on the original Windows CD, you will probably have to make a clean install of Windows from scratch.
You will need a Windows CD of the same version as the one of your Windows installation, and the Product Key, preferably the one that was used to install it, but it can be one for the same version as the one of your Windows installation.

how to do an XP Repair Setup, step by step:
http://www.windowsreinstall.com/winxppro/installxpcdrepair/indexfullpage.htm

Thanks for all this help ;-) I've not had much time this weekend but i'll try the cd-rom and floppy in another computer tomorrow. Unfortunately I havn't got access to another PSU atm.

Something I maybe should have mentioned to begin with, which you reminded me about when you were talking about the motherboard battery, is ever since I bought it and fitted it, if i switch it off fully by flicking the main switch on the PSU at the back, the mobo loses all settings and time and date etc when i next switch it on (At the start it says something about a check sum error, press F1 to continue anyway). It's done this ever since I got it around 5 months ago. I should have sent it back but thought it was just a bad CMOS battery, and by the time I replaced it with another and realised it still did the same thing it was too late to send it back.
Although this has happend for 5 months or so and never caused any problem, unless I want to overclock (and having to set the date everytime i switch the computer on!).

I'll read through your post again tomorow and try the things you've said. Cheers.

Ok the cd-rom and floppy etc works. Just bought a new mobo but it's still BSOD'ing when it tried to load windows. Though it's letting me boot from floppy now, so i'm gonna try and reinstall windows and see what happens. If it does the same does this mean it's deffo the PSU at fault? If so i'll order a new psu and return the mobo.

Sorry for the late reply again, hopefully someone's still looking at this :-P

"Just bought a new mobo but it's still BSOD'ing when it tried to load windows."

I already told you why it does that in response 4:
Quote:
"When you set up XP on a hard drive on one computer and then install the hard drive on anorther computer that has different hardware, the difference in hardware is too much for XP to handle. You can get various messages because of that, or just a blinking cursor at the top of the screen. I haven't encountered XP giving me a it had to shut down windows to stop damage to my computer message in those circumstances, but I suppose that's possible."

You can either run a regular Setup from scratch again, or if there is data on the hard drive you don't want to lose, you do an XP Repair Setup, as in response 4.
The time it takes in either case is almost the same, except you are asked fewer questions if you do the Repair Setup, and it will retain most settings you made in the original setup.