Computer boots but freezes when loading

Hello,

After booting my computer, it begins to load windows but after login and the beginning of the desktop to loads, the computer freezes. Cannot use the mouse or keyboard. Cannot use Alt, Crlt and Del keys to shut down or get to task manager. I believe it is a virus but can't any scans because everything is frozen. I can get into safe mode but of course without knowing what I am looking for, I can't remove anything that may be causing the problem. Any ideas of what I might do?