Moved to Malware Discussion.
With absolutely no details given it's a guess as to what it is and I am assuming you don't mean McAfee is on your screen all the time. But as a starter try running the free version of these two tools and let them remove everything they find.
Reboot if asked. Update them before running them.Message was edited by: Ex_Brit on 11/9/09 2:49 PM
Thanks for your time. The first tool solved my problem. It found 10 threats and removed them successfully. 'Alpha Antivirus' was the phoney that kept coming up.