The last update blocks the work of GameGuard of online game Lineage II ( http://www.lineage2.com ). This problem faced by all avast! home users, not only me.
I hope you`ll fix it.
http://img399.imageshack.us/img399/628/bfsmbjb1.jpg
→ reboot doesn`t help. there are only 2 variants: adding GG folder to exceptions or unintalling avast!