My computer will not boot up

I had the security suite virus on my PC and using advice found online, managed to remove it using CCleaner, rkill and MalwareBytes. Virus was removed, programs opened as they should, I decided to update my AVG internet security. After updating, I ran the virus scan which turned up a couple of issues which required rebooting to fix. When I restarted the computer, it just got to the part where the windows logo shows and the blue line is scrolling across and then it started all over again, just cycling around until I powered off. Can someone please advise me as to how I can fix this. I have tried pressing F8 and using last good congifuration and safe mode but it just keeps cycling without starting