Thanks,
The doc's are really interesting, but will take some time before I figure everything out
It isn't a real problem that F-prot can't scan mbr's, cause if the mbr is infected you will notice it trough coruption of files.
The problem is that if you try to fix the mbr of a win partition and it gets overwritten then windows doesn't boot up anymore.
You can simply fix that by using the original dos fdisk prog. like "fdisk /mbr" , but this can only be done in a dos environment and not under linux...