Thanks very much for your help!
I got the error msg just before the scan and then it just went on scanning like nothing was wrong.
I followed the instructions on the thread you gave me igor.
The value of "BootExecute" included:
C:\Program\ALWILS~1\Avast4\aswBoot.exe /A:"*" /L:"English"
C:\Program\ALWILS~1\Avast4\aswBoot.exe /A:"*" /L:"English"
C:\Program\ALWILS~1\Avast4\aswBoot.exe /A:"*" /L:"English"
By removing these lines the problem was fixed! Not sure though why there were three lines...
Thanks again!