OK...this is....weird. :S
I wanted to reproduce this bug today but everything went fine...like you said. I already was thinking about how to apologize to you.
But just a few minutes ago I came across the same bug.(spine wasn´t running for an hour or so) I tried to open the project containing the skinned mesh several times and spine crashed at each attempt.
Now here`s the funny part: I opened another spine file within the same folder, THEN tried to open the first one (skinned mesh) and it worked. Now I can close and open spine and every spine file again without any problems.
And I was already working within the same folder all day (without rebooting my pc - just to clarify that)
Sorry for bugging you with this strange (random?) crash. At least I've found a workaround :p