Computer freezing - suspect hardware

[ThaSensei]

Hello all,

I've got mostly all new hardware that I bought and put together myself. I initially installed Windows XP x64. The system ran fine for about a day, but then it started to freeze. Unfortunately, I can't tie it to any particular activity. I've had it freeze while copying files from an external USB drive and I've had it freeze while playing a video in Windows Media Player. The image on the screen freezes and I get a sort of pixelated shadow image (It kind of looks like really poor quality cable TV where the colors are too bright and kind of blurry), then the computer becomes completely nonresponsive (mouse/keyboard don't work) - though I am able to turn it off via the power button. Sometimes it happens right away and sometimes it'll run fine for an hour or so before it freezes. I could be wrong, but I don't think I've seen it freeze when I just leave it idle.

I have since formatted and installed Windows XP SP3 x86, but I'm still getting the same problem. I've disconnected all unnecessary hardware, though I'm stuck with a usb mouse/keyboard (as opposed to PS2). I currently have only the default drivers installed. I've tried using the drivers from the NVIDIA disc that came with the mobo but had the same problems. I'm currently running the system with the side panel removed in hopes that it's not a heat issue. I also ran Memtest-86 v3.5 at the default settings from a boot disc. It ran for an hour and completed 2.5 passes with no errors before I stopped it. I've also tried using an old CRT monitor thinking that maybe my flatpanel was the problem, still the same problem.

I'm pretty much out of ideas and I'd REALLY appreciate any and all advice. Thanks in advance!

Hardware specs:
Motherboard: MSI GF615M-P33 [Integrated video, sound, ethernet]
CPU: AMD Phenom II x2 550
Memory: Super Talent 2GB DDR3-1333 (Single) [Model W1333UB2GM]
HDD: Seagate Barracuda 500GB 7200RPM SATA [Model ST3500410AS]
DVD Burner: LG super multi SATA [can't find the model]
Logitech USB keyboard
Dell USB mouse
ProView flat panel monitor connected via VGA

[truenorth]

If you can (without spending any additional money) obtain a standalone video card --as opposed to your onboard--i would try that 1st and see if it changes the outcome. Actually as I'm sure you know there are a number of items that can cause this type of issue but i suggest starting at the video card.truenorth

[thelaymanscomputer]

Is the problem still occurring with the side panel removed? If I think heat may be an issue (and there is no obvious cause for it such as stuck fans or dust) I usually take the side panel off and face a desk fan into the case. If it still locks up you can be fairly sure it is not a heat issue. As Truenorth said, it sounds like the gpu is the problem. I notice you say it does this when you try to install the nvidia drivers - so it works fine without these drivers installed? If so maybe try downloading updated video drivers as that could cause problems too.

[ThaSensei]

just an update...I just installed a fresh copy of Windows 7 and I'm still having the same exact problem.  I've disconnected all unneccessaries, so I'm down to the mobo, cpu, mem, hdd, monitor, and PS2 keyboard.

I haven't installed any drivers, so it's using whatever Windows decided to use (judging by device manager, it looks like all the hardware was accurately identified).  While I can't completely rule it out, I don't think it's a graphics driver issue as I've seen it freeze in safe mode.  I do have a PCIE video card, but I still get the same freezing problem using that card.

I let memtest-86 run overnight and I didn't get any errors after 9+ hours.  However, as soon as I opened the memtest configuration options and then closed the options, it popped an error and froze.  I'm not sure if that's indicative of a hardware issue, or if that was an error from the memtest software.

The system locks up just copying files on the HDD - just creating a copy of a folder in the same directory.

Could it be something as mundane as an IRQ conflict?  I'm completely out of ideas...