I just cut an MP3 audio clip in kdenlive by playing it, stopping at a certain point, zooming in, moving the caret around by a few frames, pressing Shift + R to cut, continuing to play, zooming out and so on.
Sometimes, the audio clip right of where I cut it was shifted by some seconds to the right (so there was a gap where I cut it), and when I tried to move it back, the clip jumped back to its previous position and I got the error message (similar to) "Cannot move clip".
Once I saved and reopened the project, everything was normal again, the clip to the right was adjacent to the one on the left where I cut it.

I am anyway seeing this behaviour every now and then, also with video clips, that a clip is shifted or moved to another position in the timeline, and it is not possible to move it back, getting the "Cannot move clip" error message, and the only way to get out of this state is to save and reopen the project.

Does anyone else encounter this behaviour?

kdenlive 0.9.6 on kubuntu 13.04.

Yes, all the time. No idea how to deal with it, other than my current technique - save and restart kdenlive.

Okay, so I'll also give it a try to reproduce it, and file a bug report if I can.

I occasionally see this behaviour too - with video clips not audio. And my solution is the same as yours.

And of course this is a prick of a thing to file a bug report on because how the hell is it reproduced?