Primary master disk fail is very scary. Very scary. If it's not bad already it could be a sign that your hd's on the way out. That should never happen. Just to be safe I'd back up anything important to you.
It could be a problem with your cdrom as well. In win95/98/ME if your cdrom goes bad and is having a hard time accessing data, it can completely hang the computer up. It could cause you to have to restart. The only thing is, is that it wouldn't hang the computer on boot.
Does your computer make any funny noises now? Does your hard drive click kinda? Maybe a thunk? (highly scientific terms I know) Does your cdrom spin up, then down then up again as if it's trying to read something but not able to? What kind of computer do you have? Is it store bought or custom built? What OS are you running?
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"The object of war is not to die for your country but to make the other bastard die for his."
-General George Patton (1885-1945)
Member of CLAN HADB