hangs on startup

Hello everyone,
I'm just recently having a problem with vista again and it goes like this. I turn on computer and it loads to the green bar thing and it just hangs there. I've did some snooping on the forums and it seems quite a few people have encountered this but with no real solution. I just brought this computer in january and I can get into safe mode. I've used system restore to bring it to an earlier period where I knew I didn't have this problem.. But this still occurs even after. I ran the basic tests, memory diagnostic tests, chkdsk etc and everything is fine. I run the startup repair test and it could not repair it from what it says. The only major change I made to my computer was manually the service pack a couple weeks ago. Any help will be much greatly appreciated.