Computer help! Blue screen and automatically restarts, but can only use in safe mode. What do I do?

I have a dell laptop with Windows Vista. I turn my computer on and it'll come on for a few seconds and then a blue screen pops up, but not really long enough for me to read all of it then it automatically restarts. If I start it up in Safe Mode or Safe Mode with networking it will turn on. So then I tried my Symantec Endpoint Protection (Antivirus) software and it says Warning in the Antivirus section, but it won't let me do anything about it. It won't scan, it won't let me update, it won't let me repair or anything. Please help! I just had to pay for a dell on call session like last week and I can't afford to pay for another one. Thanks.