I get this error now when I start windows:

One of your disks needs to be checked for consistency

I was on MSN when I got a message from a friend saying download this pdf document when I downloaed it I saw a MOS shortcut on my desktop but I downloaded it right away, this morning I saw my computer not running at its normal fast speed so I restarted and saw that error but it's been fine for days.

I think it's from a virus or my hard drive is going, any ideas if there is a way to fix this other then system restore or by replacing the hard drive?

That message you got could point to a disk failure, specifically a bad sector, although it's not definitive. Tis error is also seen if you shut down the system improperly. Just to be sure, run a check disk with a surface scan on the hard drive. About the sytem running slow, try running an adware scan on the computer.

I also found out that other people are having the same problem, I take it it's some sort of a pdf virus but havn't found a fix for it yet.

Whats the best way to run a disk check?

Use your Windows XP CD to boot into Recovery Console. In there, type chkdsk /r C: to run a thorough check on drive C:

Or, you can run the same command in a command prompt window.