[Ardour-Dev] Suddenly refuses to play

[Jacob Wise]

Hello,

I was just working on a session that suddenly started refusing to play
at all (the culprit, I think, was multiple undos that ended up doing
weird things).  I hit play (or spacebar, or L), and the time readout
might jump a fraction of a second, but the green arrow remains lit
even though nothing is actually playing.  The Auto Play and Auto
Return buttons are greyed out and clicking them has no effect.  The
error showing in the terminal (multiple times) is:

ardour: [ERROR]: could not reconstitute MementoCommand from XMLNode.
object type = N6ARDOUR13AudioPlaylistE id = 120

This is Ardour 2.0.2 running on Gentoo on an amd64 system.

Help!
Thanks.
JW