I have the free version which keeps telling me my Virus Definitions are out of date - have tried to update & nothing happens!!!
Latest VPS is 111128-0
What do you have ?
I have 111121-1 and it is telling me the latest definition is 111127-0
Try avast repair and a reboot
For a repair of avast. Windows, Add Remove programs, select ‘avast! Anti-Virus,’ click the Change/Remove button from the pop-up window, scroll down to Repair, click next and follow.