Have you removed !avast for troubleshooting purposes, calamitag?
If and when you do, I recommend an installation of Microsoft Security Essentials if you'd like to not go without an anti virus during its removal.
Oh, and as far as the last three drivers go.. if my research is correct:
imgsf.sys - Image SFilter Driver
GenEncSF.sys - File System Filter Driver
ptfd.sys - VirtualDisk Driver
Regards,
Patrick
