Oh geeze.. yes, DEFINITELY exclude the AC database from virus scanning! Most of the virus scanners are slow as heck and open the file for exclusive access, which will give you the "lost connection" message.
I DO advise though scanning the imported items folder regularly if any imported items are placed there directly. I just don't advise scanning this during working hours.. or for that matter scanning ANYTHING except fresh downloads or e-mail during regular hours. Over the network it really slows things down!
V.
