Clean This is a special type of virus *8bit boot sector virus that runs before the operating system starts* meaning it will actually have a chance to start up just before safemode since those kind are designed to look like the core 13 processes for the operating system.
The only effective way to fully remove them all is to take a computer that is currently running to extract your information that you would like to still keep from the hard drive.
However, You will need an active monitoring virus protection that supports usb and secondary hard drive support to lock the drives from auto starting programs from them such as Microsoft Security Essentials.
* Also you will need to set the hard drive you added as a secondary in your bios so it will not boot from it, this way it will only use the hard drive once the operating system is finished booting to the desktop which your virus protection will be already running by then.*
After it's fully backed up you have either 2 options.
1.) Attempt a removal from the virus protection that your using to back up with and a secondary virus protection such as Spybot Search and Destroy from SaferNetworking.
2.) A complete wipe and reload of the operating system using a windows disk that normally should be supplied with your computer. * note that you will lose the programs installed that is not part of the Windows operating system.*