What is the version of operating system you use (Vista / XP)?
Did you receive any kind of alert/advertisements or pop-ups in the computer?
Post the DAT version and Engine version of McAfee Virus scan (Open Security center-click on about in the Right hand bottom panel-check the Build version and DAT version for McAfee Virus scan)?
Try to end the task for McAfee update exe under the Task Manager.(CTRL+ALT+Delete)
Delete the Update folder and restart
1. In Windows Explorer, navigate to: C:\Documents and Settings\All Users\Application Data\McAfee\MSC.
2. Right-click the Update folder and select Delete.
3. Restart the computer.