Spontaneous rebooting

[#1]

Running XP Pro with Asrock mobo, 512mb PC2700, other unremarkable components.
Quite often the computer will reboot spontaneously without warning, the screen goes blank and it restarts, and that's it, no warning of any kind, no variation in fan noises etc, just like I've pressed the reset button.
More often than not this happens either during the boot sequence itself, or within 5 minutes of turning it on, sometimes twice within a half hour, sometimes not again for a fortnight.
Have replaced or (temporarily) swapped many of components, but without success.
Just ordered 2Gb of PC3200 memory as an upgrade, hoping this will be solution.
Any ideas?

[#2]

Do a full Memtest run (not the basic tests) and see if it throws up any problems.
Do you have another PSU you could try?
Have you checked the CPU temps?

[#3]

First thing to do is disable auto restart so you can see the error message

Quote

Open System Properties via Start > Control Panel > Performance and Maintenance > System Select the Advanced tab and then click Settings in the Startup and Recovery section In System Failure section, clear the checkbox next to Automatically Restart Click OK and OK to exit

[#4]

Have tried memtest recently without it showing any problems, do not have another suitable PSU, no temperature problems.
Have cleared the check box mentioned by Peter Vaughan and now awaiting another failure to see what happens.
New memory upgrade, now on its way to me, should eliminate any possible memory problems.
Thanks for help.
Any other suggestions welcomed.

[#5]

Spontaneous reboots (if not memory faults) are most often caused by PSU problems or cured by replacement of the motherboard.
Most especially if you have changed any hardware a PSU fault is indicated.
Good luck with the memory.

[#6]

The spontaneous reboot happened twice again this morning.
First time got a Blue Screen of Death, stating:
"The problem seems to be caused by the following file: tcpip.sys"
"An attempt was made to write to read-only memory."
2nd time was unspecific to a problem, but strongly suggested memory problem.
At least now I have something to work on. Hope new memory will cure this annoying "feature".
Thanks all.

[#7]

hi,
i had the same problem on a brand new duel core machine running vista a few months ago.  it turned out to be a faulty memory stick. had it changed and all has been fine since.
hope this helps

[#8]

What is it with memory at present, two of Sun Blade 150's that I look after are suffering memory problems.
One just keeps rebooting. (service visit scheduled tomorrow)
And the other boots intermittently, then shuts down. (Soak testing with just one memory stick.)
Luckily Solaris logs which stick is causing the problem before dumping its core.
Chilly

[#9]

I think I may have solved the rebooting problem - maybe, time will tell!
I use Windows Diskfragmenter quite regularly, but not chkdsk.
So ran chqdsk in extended, 5 part form, from Windows Explorer/right-click C-drive/properties, tools, tick both boxes and then start, then scheduled to run on next boot up.
It seemed to find some problems, but rebooted again so fast I didn't have time to see what they were.
Hope that's fixed it.

[#10]

Your crash reboots will mean that directory entries and data entries are not necessarily in sync.
chkdsk will find a lot of hits.
You might lose data because of this.

[#11]

I was of the opinion that a standard defrag would identify the existence of directory-type problems (but not necessarily cure them). At this point you would maybe have to use chkdsk to fix the problem. Well - at least that's what I believed up to now.
I now seem to have cured my problem of spontaneous rebooting (touch wood, it seems to have gone!) by using the extended, 5-part chkdsk, when defragging failed to pick up any problems.
I am puzzled but slightly more knowledgeable.
But at least I had a good excuse to get some more memory!

[#12]

At last I have discovered the source of problem - not memory or anything that may have been detected or cured by chkdsk.
It was a faulty 2nd hard drive!
I had 2 HDDs on first IDE cable and 2 DVDs on 2nd.
Now running for over a week without a single glitch - just disconnected the 2nd HDD.

[#13]

By removing a disk you have eased (slightly) the strain on your PSU.
Actually, for IDE (depending on use), it would be inefficient to put both hard disks on one cable and two DVD's (presumably one is RW & one read only) on the other.
Most of the time it is likely that you want access to the disks simultaneously - but IDE can only access one device per cable at a time (delays can be substantial).
AFAIK Windows (unfortunately) allocates drive letters according to which cable a device is on, according to some rather complicated rules - so you can't just move hardware between IDE cables - you would probably have to reinstall Windows if you did that.
The (likely) ideal configuration is to have one disk & one DVD on each cable.