error logs
hi,
I assume that you are a windows user. so have you checked the error log for events during the machine crash? else it could be alot of things or a mixture of components which when they come to work at the same time just crash the machine...
what you can do is make an exception list. try different memories, maybe different disk with a fresh installation of windows, plug out all you don't need (e.g. pcmcia cards or usb devices).