Reaper Crashes always at the same timecode

[Fox the Reaper]

Hey how,

so i'm running my first project with reaper. Short, 30min. It's working pretty well so far, until i get now this bug: Everytime i pass the 00:02:00:00 Reaper crashes. I set there a Marker for the filmstart. I can do everything in the projekt, but if i want to start there watching, or earlier and pass, it crashes. If i set the marker to 00:02:00:01, go there and start, no problem. One frame earlier, it crashes.

Crash mean, the raindbow dot, so osx, i use 5.9 with 64bit. I have to force quit then, can reopen, can work, but if i pass again...

any ideas?

Thanks a lot and have a nice week,
Daniel.