Same here.. I had to reboot the Digitakt like 5 times in 2 hours yesterday, because it was frozen.. Mostly seems to happen when stopping the sequencer after some real time recording.. Not always, but eventually it will freeze.
I just have a simple midi keyboard to the midi in of the Digitakt just to make sure it's not being flooded with midi data, but after recording some notes in it will eventually freeze. I do not get some kind of 'exception' or error.. just an unresponsive Digitakt.
I do have like 8 midi tracks running, but no cc locks or program changes.. just note data only.. Not sure if that's the cause and perhaps I should try running less midi tracks to avoid this behavior for a while?
Hope it will get fixed soon.. for now back to Octatrack for midi sequencing