It's not something silly like the CD being scratched is it? Or you could try a Linux live CD (Knoppix, for example), to see if that works. They usually give quite detailed start-up logs so you can see if anything goes wrong and where.
Or it could be bad RAM?



I know it's not the most uber overclock ever, but I've got my q6600 to 3.3ghz (366*9), 1.296v. It seems to run stable at about 35c idle, and 55c load.
I've got C1E & EIST enabled in the bios, I've been reading about how you shouldn't really do it, but is this really such a bad thing? It's dropped the heat down nicely, and I haven't had any problems with it in the 2 weeks I have been using it. Is this enough time to declare it 'safe'?