Win 7, 64 bit OS. Running bitdefender antivirus detects trojan.sirefef.fy but can not clean it. Relevant log files to follow. Thanks much for any assistance! I apologise in advance for any delay in responding - internet is sporadic from the infected machine (unrelated to the virus and totally related to DH cutting the phone cable) which means I am often porting information from work to home and back to respond.