:P they act up at any time, it could have been, maybe the pin was left on the disc and you accidentally tapped it, or its time just came, or something just happened to happen, try running a naked build, only use the parts required to run, so like 1 stick of ram, one HDD, no extra fans, ect..
Ran a naked build. It's narrowed down to the CPU, the hdd and the PSU. I just recently got the PSU, the hdd is old and the CPU is crappy. I'd be surprised if it were a hardware issue, though, because it happened on the boot precisely after I plugged in the fan. I wouldn't be surprised, though, if I did some damage.