Norton 360 seems to have slowed my pc!

I originally had an older version of Norton Antivirus. I recently bought Norton 360 v3.0, then installed it.  Ever since all programs, not just internet explorer slowed way down. It takes a really long time to respond. Sometimes it says at the top of the window(Not Responding) Then after maybe 10 seconds, it will respond.  I have windows vista. I dont think thats the problem, because it worked perfect until i installed norton 360. Please help as this is extremely frustrating!!!

 

thanks!!!