Computer slowing down, screen flashing

[VulnoX]

Hi all, I recently built my first computer since probably 2003 (been in college and using laptops).

It is:
Abit P35 Pro
Intel Q6600
4GB DDR 1000 Ram
Nvidia Geforce 8800GT 512MB
Seagate 500GB HD
Onboard Audio - Realtek HDAudio (Can't find any model information)
Onboard LAN - Dual Realtek RTL8169/8110

I think those are the big points.

I currently do not have it overclocked, and the motherboard is set to run the CPU at stock, and is running the memory at ~800MHZ (which I had set to 1000, where it should be, but I let the motherboard set it once I started having this problem).
The GPU clock is set at 100Mhz according to the BIOS.

Anyway, sometimes when dealing with video, the computer sill pretty much come to a hault, and about every 10 seconds, the screen will flash (go all black, then come back, very quick), and the computer will have done something. Like the mouse will move if I moved it while in its frozen state, or whatever.

I noticed this happened when trying to watch a YouTube video I think it was, and once when I opened a folder that had video files in it and Windows was loading the thumbnails. When I first opened the folders, there were no thumbnails, and then at each flash of the screen, one of them would load. Once they had all loaded, about 7 flashes, the computer ran normally again.

I have also had it say my Nvdisp (can't remember it exactly) driver stopped responding when exiting Starcraft, this results in me having to restart because the screen goes to something like 320x240 and 4 bit color.

I have tried a couple different driver versions, only really the most recent official drivers from nvidia's site, and a set that are slightly newer that I got from Guru3d. (117.117 or something?) Full driver version tag is: 01/05/2008, 6.14.11.7117

I am using only FFDShow codecs, newest ones. I use VLC media player, and this happened before, and after, I recently did an complete computer wipe and reinstalled XP. I updated to SP3 and all the newest updates are done and as far as I know the newest drivers are installed.

Thanks for any help, and if I left out any information please let me know!

Thanks!

 

[Billb2]

What's the voltage spec for the ram and what is it set at?
You may have to increase it slightly with 4 sticks.

 

[VulnoX]

The spec on the voltage is 2.0-2.1V. When I reset everything to defaults in the BIOS it set it to 1.8V 800MHz (A common problem on this mobo with 1000 ram).

Last night I messed with my settings at set the memory to 999 (so 1000) and increased the voltage to 2.0V. So far it has been pretty good.

I am only running two sticks, 2x2GB G-Skill 1000 DDR2.

Thanks for the suggestion, I am giving it a try and seeing how it does.