I've started trying out the version of Rosegarden distributed with Lubuntu 12.04, and encountered a problem. I think the crash has already generated a bug-report, but with this e-mail, I'm hoping to give you a heads-up of the problem, and fill in a few more details.
I was trying to record simultaneously from two tracks of my MIDI keyboard, with MIDI channel 2 going to track 2 (specified by the "Recording filters" in the Special Parameters pane). Similarly, MIDI channel 3 was going to track 3 (again specifying that track and channel in the recording filters).
Track 2 was explicitly assigned to MIDI channel 2, and Track 3 was explicitly assigned to MIDI channel 3.
It recorded them simultaneously okay, though both instruments had the sound of the selected track (2)'s instrument (one can always hope for better, but not necessarily expect it).
The problem was at the end of the recording, when I clicked the stop-button. At that point, it crashed.
I said a few choice words, then decided to record the two tracks separately. But at the end of the recording (I think of the 1st track separately, but it might have been the 2nd), it crashed again, in the same manner.
I tried another test (the particulars of which I can't remember), but this time, instead of crashing at the end, it froze-up, and I couldn't terminate it, even with the "End Process" option you get after multiple clicks on the "Close Window" button.
I rebooted into my Lubuntu 11.10 partition, and tried the same thing, which worked without any problems (in Rosegarden 11.06). So it does seem to be a problem with the newer version of Rosegarden.