If your anti-viruses can detect it, then try re-running your computer in safe-mode with network disabled. The reason why the virus can not be deleted is because it starts up hidden as a core process when your computer starts up. (You can not delete files which are running actively on your computer for obvious reasons).
If you open your computer in safe-mode, only the CORE PREDEFINED PROCESSES SET BY WINDOWS (dunno why i caps'd) wills tart up. Afterwards, run your antivirus and it should berid the trojans. Most trojan types create a new file which creates a backdoor to your computer, rather than infecting an actual windows startup file, and even if it does, without an internet connection, the trojan host can not send commands rejecting deletion.
Best of luck, if you need to know how to start in safemode just ask.