Alright so I've looked for answers everywhere and can't figure out what's going on.
I have a pretty basic HP desktop PC (m8307c) that's 2-3 years old with an Nvidia GeForce 8400 GS.
A few months ago small flickering corruptions started flashing on my screen. I can't think of any trigger for this but they started out as a nuisance and things have gone down hill from there.
It's the a monitor issue so I updated my drivers and that seemed to solve things momentarily but the on-screen corruptions came back and then every so often everything would lock up, screen would go black, and Windows would do its reset of the display and inform me that "Nvidia Windows Kernel Mode Driver, Version 258.96" had failed.
Also, flash-based videos online would regularly stop playing normally and would turn into a mess of colors as if I didn't have the proper codecs or something. Sometimes everything would work fine, however.
Finally, in the last week, things have deteriorated to the point where I have trouble getting to my desktop without the system freezing. Even the little Windows 7 spinning "loading" circle seems to be able to cause a freeze.
Often when I restart, the computer has trouble restarting and seems to get stuck on the HP bootup logo.
I found a video on youtube made by a guy who seems to have the same problem:
I don't have any reason to believe it's a heat issue. I thought perhaps a large buildup of dust was somehow messing with things so I used a lot of compressed air and cleaned the whole case out. That didn't help.
However, I don't actually think it's a hardware issue anymore. When I go into Safe Mode everything seems to work fine so wouldn't this be an indication that it's a software/driver-based problem?
I agree with rolli59 on this one. Sounds like it's either a heat problem, or the video card (or component on the video card) is failing. The fact that only Games and Flash programs do this suggests it's a 3D rendering problem.
Safe Mode as rolli59 said, is a 2D only type interface and loads minimal drivers and such to provide a fail safe environment in which you can fix driver/software problems.
The easy way to see if it's a heat problem is to run GPU-Z and monitor the GPU temperature. If it's running over 85C then it's likely a heat problem. At desktop with nothing else going on, an 8400GS should probably show idle temps between 40-55C depending on your ambient room temperatures would be my guess.
If temps are good, then it's likely a driver of GPU problem. Knowing that you've tried updating drivers, leads me to believe it's a GPU problem. Now, being an older pre-built system you could also have a PSU (Power Supply Unit) issue as well. Perhaps the power supply isn't able to supply the power needs of the entire PC when the video cards kicks into 3D mode.
The thing with 2D vs 3D is that I've had it freeze on the Windows 7 logon screen as well as simply when opening my internet browser, it's not particularly consistent. The on screen corruptions are always there though.
I suspect it could be something other than the GPU since oddly enough it sometimes get stuck on the HP boot screen.
Regardless I installed GPU-Z and it looks like heat may indeed be an issue. It has never been an issue before and my room is usually cool/normal room temp but the idle temp right now is 74C. Again, I think I got rid of all the dust in the case and heat has never been an issue before so is there anything else I can do to reduce the heat? Is the GPU slightly fried and in need of replacement?
An idle temp of 74C is really high. I'd suggest removing the video card and blowing it out with compressed air or something. Make sure the fan and any heatsink fins are cleaned out so air can effectively pass through.
Also, you might check to see if the fan on the video card actually works!
I'm really starting to think that this is not a GPU issue because I'm having a lot of trouble booting. I have to turn the computer on and off a few times before I can make it to Windows successfully. I really don't know how to isolate the problem. It could be a motherboard chip issue...or maybe some hard drive sectors are corrupted causing it to mess with video drivers, etc? I really don't know. :S