The drawing is crashing on a cross section layout.
I'm sure it's a file problem and I'll work it out. Not the first corrupt ACAD file I've had to deal with.
Also, I believe the reduced file size started when I upgraded from C3D 2010 to C3D2012.
There are lots of posts about problems with Recover. I can't explain why it works for some but not for others. You might find an answer if you go through them.