Windows XP Professinal crash

Here is my problem: on my pc I have two hard disks; one has Windows XP Home Edition, the other Windows XP Pro. About a month ago I overclocked my CPU E8400 from 3.00 GHz to 4.00 GHz, and run Prime 95 for 16 hours with no errors. Right until then, upon booting, I would get the black screen with the option of the two OS to choose from; a couple of weeks ago this double option on the black screen ceased to show up, and I could only boot into my XP Home edition, while the pc would crash upon loading XP Pro;I reinstalled XP PRO but the problem still persists today. I had a friend of mine check the hard disk with XP Pro just in case, but it seems to work fine. By the way, last nite I realized my CPU is running at stock 3.00 GHz, and not the 4.00 GHz I had overclocked it to. Anyone understands what the problem could be? Please help me, I really don't understand what is wrong, thanks for any suggestions, I hope I was clear enough, any questions on the matter are welcome and wil be answered to the best of my knowledge,

ENRICO

 

My ASUS mobo has an automatic BIOS reset to default function if the CPU hangs due to OC so that may be your case too. As to corrupt XP Pro, only thing that I can think of is to repair the MBR but reinstalling Pro should have taken care of the MBR issue.

 

I have got as ASUS board as well, p5KE, and last nite I took out the battery to make sure that would take all BIOS settings to default values. Besides, as yo say, reinstalling should have taken care of a possible MBR corruption, I really don't know what else to do. But thanks for your insight :wave