Hardware or SP2 Issue?

I'm not sure what is causing my issue her. After I installed SP2, the computer had a hard time booting. It would hang with the hard drive light lit up and the only option would be to hit the reset button. This would happen anytime, sometimes while working in a program, sometimes while booting up, at any point after the POST. after a couple of days, XP reported that a file was missing during boot up and replaced it. I can't remember hwat the name of the file was. It worked fine for about a week. Now, it reports that it can't find a bpptable device after the POST. It will do this a couple of times, and then boot properly.
The POST reports that the hard drive is fine, but I suspect a hard drive problem. It's a Western Digital hard drive. Any thoughts?

Go to the Western Digital Site, get there program that diagnose hard drive problems, if it finds a problem its your drive.