Anti Virus Won't Launch, Gives Error 8504 etc

Hi all

My Norton Anti Virus is acting strange... Clicking on the program's icon results in the error screen I have attached.  At first, the error I was getting was 8504,100.  Now it is 8504,104.  When I right click on the taskbar and click LIVE UPDATE, etc, I get a second error box relating to the "ENGINE".

I ran the Norton Power Eraser, but it didn't detect anything I couldn't identify, or that the Norton community thought was unusual. 

Norton Utilities 16 runs normally.  

I am on Windows 7 Pro.