I have this error occasionaly.  There is only 1 model in the drawing, and I can open and check the model, and it is NOT rolled back.  I can not close the drawing, ctrl+Q does nothing.  I can not even close SW, I have to use task manager and end program, thus losing anything since last save.

Anyone else have this?  Is there something I can click or do?  Or is this a quirk of my system maybe?