Have you had any recent virus or malware issues? If you have experienced any thing this link has some good information to help you Please be sure to follow the recommendations here and run the Stinger scan which are mentioned.
You may also want to try running McAfee Virtual Technician http://mvt.mcafee.com to scan your computer for McAfee issues and let us know if it finds any. MVT will generate a session number and please post the details here in this thread.
You could also try to contact Technical Support which is available 24/7 under Useful Links. They could do a remote connect into your computer to see if there is any conflicts and have many tools available to them.