It seems still trouble with my Win 7 (32Bit) Home Premium which is at my device manager still detected that “avast! Firewall NDIS Filter Miniport#258” have a trouble.
I am not sure is it caused by OS or avast! engine.
I’d suggest installing v5.0.499 from scratch. The 499 installer does some cleanup before installing the NDIS drivers, and chances are it will help in your case.