[LAU] Ongoing problem yet unsolved

First thought it was a qsynth problem but it his everything, across the board! I fire up a program, qsynth, qtractor, etc. I simply cannot connect (in qjackctl or qtractor's or qsynth's connection pane) to a MIDI output device. Repeated tries will eventually crash out. Qsynth will run OK with jack not running (latency not all that bad, either!). Qtractor would not connect, even without jack running, but the first try with jack might has locked out further tries. The MIDI will connect up fine "locally" with no such program running, i.e., I can connect the keyboard to an output device and play it. I have no .asoundrc or conf file. Any help appreciated because I am eager to try the new qtractor!