I voted "Anything with DRM", however, since your all canning Norton/Symantec I thought I'd add my two cents.
A while back we migrated from Symantec Anti-virus CE 8.1 to 9.0. 9.0 will scan pretty much anything coming in or going out and I was surprised to find that on one machine, it was detecting email being sent and scanning it. First thing that sprang to mind was that there was a mass mailer running on the machine, yet Symantec failed to detect anything. It would detect and scan the emails being generated, however it wouldn't detect the mass mailer that was sending them. A quick Panda scan found the exact cause and stopped it dead in its tracks, good one Symantec.