I recently had a windows (Vista) update.
I think this is the 4th or 5th time, windows has done something which messed up another device.
Unfortunately, I cannot do a system restore to before this.
It says some file is missing.

I've found one codec which lets me watch dvd's in media player, with decent vocal sound (sound effects is normal). I cannot play .mkv (HD) movies with this one.

Another codec lets me watch the .mkv movies fine, but then there is no vocals at all, although other sound is fine.

Kind of gave up on the search for codecs.
Summary, Vista is a piece of shit.