Yes, it's a fairly well known issue.. ALWAYS uninstall the previous version of VirusScan before installing the new version.. Don't depend on the new version to correctly identify or correctly uninstall the previous program.
The correct uninstall process depends entirely on the previous version of VS.. There are correct uninstall instructions for such we'll need to know the specifics of the old version.. Version number, retail or corporate, etc. For retail versions, doing a little research for the MCPR.exe removal tool might help.. As to the corporate versions, we'll need the version number to provide the manual removal instructions.
Hope this helps.