Klaus,
I use the same system as OpenText, as I originally started with that system, before I switched over to SongBook.
I've updated to 2.0, and all my midi files work properly. If so, OpenText files should work as well.
When I was using OpenText, I had to create a specific Midi Setup configuration. OS2.0 resets the midi setups to factory.
So it may be that you have to recreate the midi setup file that you did when you started using OpenText.
Hope this helps,
Fred