If it won't load Windows normally, have you tried booting it into Safe Mode? (Press F8 repeatedly, as Windows tries to load, until you're offered the option to use Safe Mode which, obviously, you should accept).
If you can get into Safe Mode, sometimes simply shutting down your PC and then starting it again will clear the problem. (Don't just use 'Restart'. Close everything down completely, wait for a minute and then boot up again).
If you can get into Safe Mode but the problem doesn't self-clear, or if you can't get into Safe Mode at all, please post again.