Windows startup problem

Hello,
I am having this same problem ... stuck on the Windows start up screen for hours ... the lights on the computer seem to show progess of the computer working, but I am beginning to wonder. I am suspecting a virus on the computer and there am trying to scan the virus by using the safe mode but this can't fix the problem.

Any suggestions on how to find out if a virus is causing the computer to not be able to get by the "Windows is starting up" screen? Thanks.