Vista - Hibernate shut down not working after Vista updates

I bought a Dell Inspiron 1525 with Vista Home Basic over a year ago and have had endless problems with the hibernate and shut down. With both the laptop would start the process then almost immediately reboot. I have reinstalled Vista 4 times and it worked fine for about 2 days. I have been blaming Dell becuase they could not fix it. I had a suspicion that it could have something to do with windows updates but could never pinpoint the exact one.

This week I reinstalled Vista one more time. Everything worked well until I installed Vista SP1, then the hibernate and shut down problems were back. I did a system restore to remove the update and my laptop works fine, so the update is the culprit.

My question is: Is there a fix for this or will I never be able to update to SP 1 or 2 and how does that affect my system?

Thanks