win xp pro sp3 w/all updates, avast free antivirus 17.4.2294.
In the event viewer system log I get NetBT error event id 4311, Init failed because the driver device could not be created.
And why do you think it has something to do with avast ?
Hell yes:
HKLM\System\CurrentControlSet\Services\NetBT Start value must not be set to one; Instead set it to 2 - Reboot computer - Problem solved.