Try a right click on the shield and check for updates.
No other AV installed or was previously installed?
Try running this program then update
Not behind a proxy see
http://service.mcafee.com/faqdocument.aspx?id=TS100291&lang=en_US&prior_tid=2&An swerID=16777216&turl==http%3A%2F%2Fkb.mcafee.com%2Finfocenter%2Findex%3Fpage%3D c ontent%26id%3DTS100291%26actp%3Dsearch
There is a manual way to update but first see if any above works.
Please try the following steps, it may fix the problem
Click on the below link
The above will give you the latest Virus Definition for the McAfee Security. Once it is done try updating the McAfee security and check the
Status of your issue.
Any Queries please post on this thread. Thanks