It may be coincidence but there is a thread on the VDR mailing list right now where someone is discussing the VFAT switch. It seems that one of the functions of that switch is to replace colon ( and other suspicious characters in recording filenames, since the filesystem character set on M$ platforms is more restrictive than on Unix. Also VDR 1.3.32 now uses dots by default within filenames in place of colons. I'm not sure how this related to your problem though, unfortunately.
Dave
Dave