Hi,
unfortunately, most of Windows infections cannot be directly
cleaned by avast for Linux. Generally, avast for Linux will only be able to repair macro virus infections.
One of the reasons is that cleaning a virus not only removes the stuff from the individual files but also fixes registry, startup associations etc etc.
If the thing you're dealing with is the Parite virus, I recommend downloading and running the
avast! Virus Cleaner - a small Windows-based applet that will quickly remove the infection.
Cheers,
Vlk