basically, you have what I call an evil configuration. Not only 64 bit cpus experience this, but even people on pentium 4s get this. Like mentioned, it can be graphics related, or ram, but it is tied into memory management. I see you are running norton anti-virus. First step is to get rid of that program and see if you still get any errors. Since you arent getting any IRQs I assume you have a good clean setup. without driver issues. If you got rid of NAV and still get the crash, try changing your ram speeds and latency settings in your bios. The ultimate solution is to replace the ram with a different design and speed. If all fails, bring that sucka to a pc shop. I know we have our pride, but they really help you out.
[root@root root]$ su