Can you run FRST? If you can , follow this instructions, attach here logs.
http://forum.avast.com/index.php?topic=120531.0

If you can’t run FRST, follow instructions posted above for creating and running OTLPE live CD.
You need to create OTLPE live CD on healthy computer. Then boot OTLPE on infected computer.

I need to see or FRST.txt or OTL.txt log. Without thouse I can not help you.