I've dealt with this annoying, common problem a few times. Follow these steps:

Download this :http://www.technibble.com/rkill-repa...l-of-the-week/ (r-kill)

This essentially terminates the .exe for hard to kill viruses.

Download this: http://www.malwarebytes.org/ (malwarebyes)

This is an excellent program. After killing the exe, malwreabytes was able to succeed where three other anti virus/spyware programs failed

NOTE: If you cannot install these programs due to the virus fear not.

-Boot to Safe Mode

-If you were unable to install malwarebytes before, do so now.

-Run R-Kill
-Run Malwarebytes

Your problem should be solved.