Try using HijackThis and upload the log to http://www.hijackthis.de/ for analysis. That should tell you which processes are safe to remove (or even directly identify the culprit).
Edit: It also allows you to delete bad registry entries, which should remove any errors you may get after deleting the .exe.
Edit: It also allows you to delete bad registry entries, which should remove any errors you may get after deleting the .exe.