Dell InspironE1505 cold boot problems

So I have a Dell InspironE1505 XP is loaded on it and I have never had a booting problem with it until now. I upgraded to internet explorer 8 and suddenly I was having cold boot problems. The screen would freeze on the cold boot, now it freezes or goes to a black screen. It will only power up if I turn it off and then on again and choose to use the last good configuration or safe mode. I've done several virus scans, ran a diagnostics test 2 actually one from the laptop itself and the other from the Drivers and Utilities dell cd, everything passed. I recently lost my hard drive and the guy that fixed it put AVG Anti virus on it I was wondering if that could be the problem? Also my battery is now severely dead, and my laptop won't start without being plugged in.....could anything else go wrong???!!