Is it rebooting over and over into safe mode?
Did you try to force safe mode to load from msconfig, some malware programs erase the safe mode keys in the registry or block safe mode from loading, if you forced it to load safe mode from msconfig you will have to edit the boot.ini file. never force safe mode this way unless you know the computer is malware free.
If it is rebooting from a BSOD so fast that you can't read it hit F8 and select don't reboot on error.