@WALLONN7
If you mean WebShield, double check you have the latest Network Interface drivers available for your system. My problems were fixed by that, and if the problem happens for Vista it's probably the drivers you have currently are a bit old.
@Alex412
Those sorts of crashes are often caused by out-of-date video drivers. Have a look and see if you have the latest. Its not uncommon for a Microsoft Update patch to cause this too which might have installed in the same reboot as the Avast update, might be worth checking this avenue as well. I believe KB3097877 recently had some problems with some Office apps, and confirm you have the latest Office service pack.