NIS 2012 killing my comp with scans

I have installed NIS 2012 and ive just turned it on 20 minutes ago and the hard-drive is going CRAZY!! my computer and browser is almost unresponive - i have checked and its norton using 20-50% CPU and scanning disk - I just run a FULL scan yesterday and have monthly scanning off.

 

3Ghz Single Core CPU with 1.5Gb ram, XP SP3 and 160Gb SATA2 hard-drive

 

this sounds like its doing another full scan...why?

 

can i stop it from doing all automatic scans?

 

enabling silent mode has done nothing too, did not stop the scan

 

 

thanks