If that fails, and you are able to boot either in Safe or Normal Mode, you can run Rkill to reset the .exe association and stop most processes.
RKill is a program developed at BleepingComputer.com that was originally designed for the use in our virus removal guides. It was created so that we could have an easy to use tool that kills known processes and remove Windows Registry entries that stop a user from using their normal security applications. Simple as that. Nothing fancy. Just kill known malware processes and clean up some Registry keys so that your security programs can do their job.
So in summary, RKill just kills 32-bit and 64-bit malware processes and scans the registry for entries that would not allow you to run various legitimate programs. When scanning the Registry, Rkill will search for malicious Image File Execution Objects, DisallowRuns entries, executable hijacks, and policies that restrict your use of various Windows utilities. When changing Windows Registry entries it will create a backup of these entries and save them in the rkill folder on your desktop. Each registry backup will contain a time stamp so that the backups are not overwritten on subsequent runs of Rkill.
Since RKill only terminates processes and does not remove the offending files, when it is finished you should not reboot your computer. If you do, these malware processes that are set to start automatically, will just start up again. Instead, after running RKill you should scan your computer with FRST and post its reports, FRST.txt and addition.txt. If there is a problem after running RKill, just reboot your computer and you will be back to where you started before running the program.
RKill can be downloaded from the following location:http://www.bleepingcomputer.com/download/rkill/
There are three versions. If the .exe does not work, try the ,com version. A report, rkill.log will be created in the root directory, usualy C:\. Post that report on your next reply