Adobe Premiere Pro CS3 Major Problem

Alright, before I give you my problem, let me supply you with my pc specs:

Windows XP Home Edition Service Pack 3
Intel(R) Core(TM)2 CPU
6420 @ 2.13GHz
2.0 GB RAM
49/140 GB Hard Drive

Ok now to my problem. Today I finished a 4 minute long video. I used the Adobe Media Encoder to render my files and when it was at about 74% complete, my entire system/computer shut down. This has never happened to me before and I have rendered files of even larger length and size and there has never been any problem. I tried multiple times with multiple different file types and still, it shuts down. There are no special effects, no titles, no anything. Just pure video. The third time I rebooted my system and tried rendering my video, I opened up the task manager and noticed that before the rendering, my CPU Usage was at an average of about 5%. I started the rendering process and that 5% shot all the way up to 100% and stayed that way until my computer shut off. By this point I was out of my mind. I installed spyware removers, installed registry cleaners, defragmented, cleaned up my disc, turned off my virus software, etc etc etc. Still, nothing. Keep in mind, this is NOT an overheating issue. My computer is doing just fine with heat. Finally after about the 10th time I gave up and came here. Any help?