Error in polymorphic virus code

I have a program which uses access database file. Yesterday my access file data was lost suddenly and it showed just 4 kb in size. when i scan any folder using avast4 home edition all files are listed with the message - error in polymorphic virus code. please help.

I believe these are two separate problems

a) shortening files to 4kb - this should not have anything in common with avast or its operations
b) error in polymorphic virus code - this most probably means that those shortened files now pose a internal problem to our scanner. Please pack them and send them directly to me. My mail is [my nick] at avast dot com.