I also got this problem once I upgraded to Avast 7. I have Windows 7 Ultimate 64bit.
I tried to fix it by reinitializing the Windows offline files database, but once I made one of the network folders always available, the Sync Center icon in the status bar got lost, and I could not synchronize anything.
If there is no immediate sw patch for that, can you let me know:
Is there a shield that can be disabled to make the offline files synchronizations work again?
if not:
Is there a procedure to go back to Avast release 6?