Computer Consistently Shuts Down....Reliability Monitor Says if's from Service Pack 2 ???

My Computer about two months ago started shutting down on average once a day, then every other day after that would shut down on a more frequent pattern. Toward the last day it would shut down and I would re-log in several times. Then, it shut down and would not start. I took it to get repaired which was a substantial amount. I didn't get the pc back when I was promised, about a week late.

It's starting this pattern all over again I think. The technician told me he took out a virus, but I don't know if he really did or not. I have Semantec Endpoint Protection as my antivirus; it comes up clean when scanning.

I was running a program when it shut down the last time. So when I booted the computer back up I uninstalled that program. I was thinking that might have worked. I was thinking that program may have conflicted with something to make it shutdown, because it has not shut down since then. But then again, it shuts down at different intervals,

I viewed the Reliability Monitor for my computer, and it states the shut downs have taken place eleven times starting 6/21/11 thru 7/13/11. It also says the Service Pack 2 I downloaded a couple years ago is the culprit.

I need to know is this possibly a valid solution?

Should I reinstall the Service Pack 2 and reinstall it? And, is it actually necessary to uninstall it first? Can I just download and run the software without uninstalling the old SP2 I currently have running now?

I know you must have Service Pack 1 before you can download SP2. That's where Im getting confused because if I have SP2 now, that mean I no longer have SP1. Therefore, I wondering if I need to download SP1 before my computer will recognize the SP2 I all ready have, but needing to reinstall?? (Sorry if I made this hard). :emotion-41:

Oh, My computer is a XPS 435 mt--i7core, 64 bit.

Thank you so much,

rewilkins2