Norton MAC Crashing on Virus Scanning?

So I just bought norton for my mac opperating on 10.6.8 and I've now done two scans of my whole computer (there are NO timemachine volumes included) and I get the pop-up window that no viruses were detected but when I close that window i can see that the prgress bar was not fully completed, in terms of total files scanned, and Norton is fully un-opperational (CRASHED) and must be forced shutdown...needless to say, it is not giving me any confidence that it is indeed finding my problem..

 

any help??