first you can start by downloading the free version of avg antivirus from www.grisoft.com (this will involve a hassle free registration process after which you will be given the download link and the installation serial no thru your email) after installing avg antivirus make sure u update it and then do a full scan of your machine all the while keeping a close watch on the location of the file or alternatively you can do an isolated scan of suspect files , pinpoint the exact location of the truant file and then remove it either in normal mode or if this doesn't work get into safe mode and delete the file ... this should do the trick...run avg antivirus again and ur problem should be solved ...