I am not sure, but as a workaround you might want to create a .pls-file. This works for IP-streams - perhaps also fo files? I'll give it a try....
EDIT: HTPC sold - "Try-out PC" has corrupted MP. You try yourself. See if .pls-files are listed in setup.
Use:
Code:
[playlist]
numberofentries=1
File1=
Title1=
Length1=-1
save as [nameofmovie].pls