Unable to do Virus Scan

I have a MacBook Pro 10.7.2 laptop with the latest Norton Anti Virus program installed.  Even after updating the program...when I try to run a scan, I get this message: The scan failed because of a scan engine problem.  Run LiveUpdate to get the latest version.  Attached is the file SymantecInfo.  Please advise what I need to do.  I keep updating but it does not fix the problem.  Thank you.

Kevin