Some viruses will block or disable a anti virus program. Yours sounds like a command is being issued to stop the install of the program.
Now to run stinger do the following.
1> Disable the restore points. The nasties like to hide out in the restore points. NOTE>>>Disabling the restore points will delete them.
2> Boot to safe mode. This limits the services and drivers to bare minimum.
3> Run your antivirus, stinger in this case.
4> Run all your ad/spy/malware tools.
5> Boot back to normal mode
6> Defrag and reboot.
This should get it out. Now try installing your antivirus program. Oh and after you run that one in the same manner don't forget to turn the restore points back on.