Computer restarts randomly. Please help.

Hi, I'd like some help with my laptop.

It a dell vostro 1500, Core 2 Duo T7100, 1.8GHz, 2x512MB of RAM, Nvidia GeForce 8600M GT, Windows Vista home basic.

It all started one day when I ran CCleaner. It restarted. I tried again, same result. Then it continued to the point where every time I downloaded something: anything. I backed up everything, and clean-installed vista. Everything running fine, even CCleaner. After re-installing and configuring everything, all fine. Then the next day it restarted again using CCleaner, then downloading. I clean-install again. Same results, all fine. Now it started again! it restarts with CCleaner, and when downloading anything, even when browsing the internet! the only way nothing restarts it's when using safe mode (like I'm doing now).

All I have installed is the usual Winrar, ccleaner, firefox, ... plus my videocard drivers (surely not a problem, because I had been using the same one long before problems started), DirectX 9, and Microsoft Visual C++ 2005 Redistributable. Windows Defender says there are no viruses, Microsoft Memory Diagnostic tool says no memory problems, device manager says both the CPU's are running fine... Please help!

 

frist,you should know the CPU temperature,if the temperature not too hight.you should remove one of you ram away and try again.
if you laptop also restart ,I think the best way is reinstall you vista,
because some virus could not be detected.

frist two step will take you 5min,and you also could down a software called ram-test,a free software,to test you ram.

 

Well, according to SpeedFan, when running normal applications such as firefox, or office, I get average 31 degrees celcius on both cores, but when I fire up a high end game like bioshock, it goes up all the way to 50. But it doesn't restart when I'm playing, just when using normal applications. As for reinstalling vista, I tried that 3 times already, so... When I get home I'll try swapping my RAM modules. Any other suggestions?

 

I think there was some think wrong with you system,and I cann't fit it,because I meet it one time and without clear up the problem.
The best way is reinstall vista. good luck

 

my wife had a similar problem with her 1720. We contacted dell - they found the dump files from the shutdown (the reboot is probably caused by a crash). That dump file will have the cause of the crash.

I would also do a hardware diagnostics test and see if you get any errors - my wife's problem was her DIMM RAM modules.

 

Oh, really? Where can I find those in Vista?

 

It's most likely the RAM too as he mentioned. Just run memtest86 and find out if that's true.

 

well on a Dell you need to shut down and press on "On" button while holding down the Fn key. But this is Dell Diagnostics - I don't think it's Vista.

I ran both Dell Diagnostics and memtest86. Both showed errors. Then I replaced the original DIMM and Dell Diagnostics showed all clear, but memtest86 still showed errors. But no crashes. So for some reason memtest86 found errors although there were none (although none that caused a crash).

I have now put in two new 1gb DIMMs (replacements for the ones I bought and sent back) and all is good - no more crashing.