Computer Shuts Down

Greetings,

I'm experiencing a very weird problem with my computer. Every time I try to perform 3D tasks, such as playing video games, my computer shuts down - actually, my monitor fades to black even though it remains on and my computer still appears to be working. When this happens, I can't do anything except manually restart the computer. This only occurs when I play video games that seem to be in 3D. I have inserted old 2D games (i.e.: The Sims, Starcraft...) and I can play them without interruption, leading me to believe it has to be something related to my graphic card or power supply unit.

I didn't have this problem before I began to play Empire: Total War (which is a bit taxing in term of power requirements). All of a sudden, during gameplay, the computer crashed and a smell of burned plastic made its way to my nostrils. I waited for a while, and then opened my case and noticed my graphic card was clogged with dust (could it have caused it to overheat and fry?). So, I cleaned the whole case, fans, PSU, graphic card, and so on. I made sure I had all the latest drivers installed, and when I tried to play the game again, the same thing (that I described in the first paragraph above) happened. Can anyone help? Thanks in advance.

Here are my computer specs:

• Operating System: Windows XP Pro, SP2
• Processor: Intel Core 2 Duo E6400, 2.13 GHz
• Memory: 2030MB RAM
• Hard Drive: 1.98 GB
• Video Card: NVIDIA GeForce 7900 GT/GTO
• Sound Card: IDT High Definition Audio CODEC
• Power Supply: 450W

That burining smell is your key indicator that something inside your system was just fatally damaged. Although it's always possible the power supply blew, all signs point to the video card. whichever it is, the part must be replaced.