A new problem arose since update to version 5.1.864: I have a program installed that came with my webcam which is "Microsoft Lifecam". Since the update to version 5.1.864 this program can not be run any longer, it repeatedly crashes with the message that "Lifecam" faced a problem and has to shut down (allowing me then to send the typical problem report to Microsoft). I tried two versions of Lifecam, an older 3.2 and the latest 3.5, both show the same behaviour. I put my whole computer (running on XP Ser.Pack3) back a few days and started then to reinstall all latest changes I did, step by step. Lifecam worked fine - until in the last step I updated Avast to 5.1.864; so I have to assume the bug comes from there!
deinstall and reinstall of "Lifecam" was all tried, nothing showed any progress.
If somebody has an idea - welcome!