"Full scan" didnt work?

I tried to run a "Full scan" yesterday but failed to do so because no matter how much I clicked on the "Full Scan" button nothing happend, although "Quick Scan" worked.

 

What might have caused this? Is there any known malware that Norton may know of that have caused this behavior earlier?

Googling this problem there seems to be atleast a few more than just me that have encountered this problem.