One method I have found that works very well when cleaning a virus that stops you from entering the safe, normal and command prompt mode is to use another hard drive with windows 7 or windows xp on it. Just set it up as the primary drive. Connect your origional infected hard drive up as the secondary drive. You usually do not have to activate it or install windows updates. It will need the ethernet driver installed so it can access the internet. Download tdsskiller.exe, combofix, malwarebytes, spybot 2.1portable and super anti-spyware portable from the internet. Run each of these in the order above. When they have all been run shut the computer down and reconnect the original hard drive by itself. Try rebooting the system and see if it will now boot properly. I would advise to rerun the above programs and choose to update them in their selected programs. Some other programs to run are trend house-call online scanner and eset online scanner.
 I have found that this method works very well with viruses such as the FBI viruses.