Have just given up on version 5 and installed Microsoft Security Essentials instead. After several days of trying to get version 5 to work I have now uninstalled it and gone to Microsoft for the first time ever. My problem was that each time I rebooted, the whole system would just hang. The only way that I could use Version 5 to was to use the Hibernate option. If I wanted to do a total reboot I would have to close down Avast and restart it after the reboot. I am using XP Home Edition.
Final straw was when the whole machine hung when I went into emaIl (I use Thunderbird) after leaving the machine idle for a couple of hours. I had to power off and the machine hung when I rebooted. This is after trying all the work-arounds that I could find for the various problems encountered.
Shame, as I really liked the look of the new version. I will try re-installing it in a few months time.