My friend just bought an HP s3120n slimline PC with Windows Vista Home Premium a few months ago and it has been working great since then.

Just yesterday, in the middle of internet browsing, the PC began to lag very badly and restarted itself. Upon restarting itself, the PC would not boot up. He gets a message saying "DISK BOOT FAILURE, INSERT SYSTEM DISK AND PRESS ENTER."

He has no floppy drive, so the system isn't trying to boot from there. When I took a look at the computer and tried to boot from the Windows XP disk, I see that his entire hard drive is unpartitioned space. WTF? Did his OS become corrupt?

I ran a scan of his 320GB Samsung hard drive with the Samsung HUTIL hard drive diag. utility and it passed all tests. I am about to reinstall Windows Vista. I feel like this problem will take more than an OS reinstall to fix... I don't want his OS corrupting in the future and have him lose all his data again. Any idea what may have caused this and how to fix it? Thanks

The only times I have seen this is when a drive has over-heated <-- that was also a long time ago, I think these days drives are a lot more robust. It's very unlikely that his OS would just become corrupt - it could be a Virus/Trojan. Double check that all the cables are fitted correctly.
Irrespective of what happens now is a good time to reiterate the need for backups!

UD.

One thing to try - boot from any windows xp or vista cd and get to the repair console (command prompt like) screen and do:

Fixboot c:

Chkdsk c: /r /p

after that see how it boots, or post back to me if your having issues

does it matter if i boot from vista CD or XP CD? His OS installation was vista, but I only have an XP CD. This shouldn't be a problem right?

xp cd will be fine just select the first available option to repair by pressing R