This post may be a little long but bear with me as it is a very strange problem.

OK. I actually think I had the exact same problem... [Moderator's edit- Just for reference, this was split from the following thread:]

my system stats:

AMD Athlon XP 2400+
Gigabyte GA7VAXP Motherboard
Leadtek Geforce Fx 5900 Ultra
1 GB Dual Channel Corsair XMS DDR 3200 RAM
Soundblaster Audigy 2 ZS soundcard

Ok so the problem started about the end of November. I had the same issues as stated above except what happened with me was random colors would start flashing across the screen. Then the screen would black out and maybe pop up a message that it was working out of scan range. I would reboot it it a may or may not get a problem on the windows screen. Way back end of November the problem was not frequent at all. The more I rebooted, however increased the frequency. By the end of December I couldnt use my computer any more. 95% of the time I booted my computer up I would get the wierd colors/lines right on thewindows loading screen then the monitor would black out. The thing was there was that 5% of the time where it worked perfectly...for a certain amount of time. All things ran normally that 5% of the, movies, everything.

This is when I started doing a series of tests. My card is in a big case with a huge heatsink, I managed to open up this case and I dusted everything out...I removed the heatsink and made sure everything was clean underneath. It wasnt some dust had gotten underneath, I cleaned it out and put some new stuff on so I would get a connection when I put the heatsink on. Put it all back together and turned on the worked perfectly for 2 days, no problems. I think it's fixed when the problems start happening again and worse than ever...

As you can imagine I was frustrated when the problems came back. by this time I had checked the warranty on my card and I was a day over the warranty date for the retailer. Too bad. One of the times I was able to get my computer running, I used the software Driver Cleaner 2 to remove all traces of my graphics card drivers from my computer. I then installed an older version of the nvidia drivers that I knew worked. This didnt fix the problem, as I was a hardware problem.

I then moved to my laptop and put a newer version of my card's bios on a floppy. I then turned on my desktop and used the floppy to backup my old bios and flash the new bios. Suprisingly, after computer worked for two days. I haul my computer back to school and just when I think I have it fixed, I get the problems again. At this point I was fed up with my card, I start contacting Leadtek about having them repair it. They tell me to talk to Newegg even though my warranty expired...I havent gotten a response back from leadtek since I sent them the message that my warranty for newegg was expired so it would do me no good to talk to them.

Meanwhile, A friend was kind enough to lend me a graphics card he couldnt use at the moment because his motherboard didnt support AGP 8x. It's an ATI 9600 256 mb, dx9 supported. I put it in boot up the computer and have no problems. Played a little half-life 2, watched some movies to test it out and it all ran smoothly. Just today I was loading up a new map in hl2 when I get this wierd noise in my headphones...Needless to say it did not sound good. Immediately after my screen blacks out I waited a few seconds to see if my computer would do anything and I shut it down. When I rebooted, windows began to load ok and I got to the login screen. I clicked my name and entered my password and right at that moment when it tried transitioning screens to my desktop, the screen blacked out. I took out the graphics card then and felt it for wasnt even warm. I checked it all thoroughly for burning, etc but it looked to be in pristine condition...just like my previous leadtek card. The next time I booted up the computer I got to the desktop, I immediately checked to make sure I could adjust screen settings, etc with my card. No problems. I then tried booting up Half-Life 2. Oops...screen blacks out again. At this point I'm mad because I dont want to have to owe my friend $100 and have to worry about getting a new card for myself...

I have a feeling something else is causing this problem with the cards....but what? I should note that when I tried a TNT2 in my system, it worked fine...but I only tested it for 2 days. I tried to be as accurate as possible in this report and, I hope, someone knows something that may help me.

I am now going to see if I can find a friend with an AGP 8x supported motherboard who will be willing to run my card for a few days and see if it works. If the card has problems on their system then I know I am treading in deep water without a life preserver.

Oh aslo one other thing, I did test several different types of monitors and experienced the problem on each one.

Just an update. I was able to test the Geforce Fx 5900 Ultra on another computer for a short period of time and didnt encounter any problems. Granted I didn't try it for 2+ days but now I think it's safe to assume that the problem may be with my motherboard. Any thoughts/suggestions?

The problem of course, is getting my hands on the correct motherboard...I dont want to spend the money on it if that's not what's causing the problems.

I have the same problem, I have not quite figured it out yet but have had it suggested that it has something to do with the amount of RAM used. It does not happen all that often but have noticed it does seem to occur when using a lot of memory, so that's worth a shot. A little extra RAM never hurts