Error message - The Vullnerability Protection Engine has been corrupted

I have recently started getting the following error message whenever I start my computer:

 

ERROR

Ther Vulnerability Protection Engine has been corrupted and could not be used.  You should run Live Update immediately.  If the problem persists, please try re-installing this product.  Your computer will not be protected.

 

I have run Live Update but the problem persists.  I am not sure how to reinstall the product.  I purchased it online in 2007 and have been subscribing to updates ever since.  (I can't find an associated .dmg file)  I am using Norton Antivirus Version 11, on a Mac PowerPC.

 

I welcome advice on how to fix this problem.

 

Thanks.