District 9 issues

AFAIK, you cannot do forced subtitles in mkv. You either get all of them or none of them.

Interesting note on this movie:

Watching it with subtitles on throughout allows you to see/hear exactly what all the reporters and news reports are saying in the background. There is some very interesting tidbits that I never heard/noticed until I was able to read it. Bloody fantastic film.

I've done forced subtitles in mkv with Taken, no problem.

You need to make sure you actually have created a forced sub file to include when you create your mkv.

I run the english subtitle file extracted by Hd-dvd bluray stream extracter through BDSup2Sub. BDSup2Sub will tell you if there are any forced subs. If so, you can save just the forced subs. then include this file with the audio and video files when using mkvmerge. You should be good.

---edit---
just re-read you post - sounds like the mkv is built correctly as you get the forced subs in vlc. Sorry, I don't have any expereince with media portal. Does sound like a player config issue though.