[racket] how to break w/out losing?

In 5.1.3, I was several steps into the Python Challenge when DrRacket
suddenly started spinning (while accessing URLs).  The Stop button was
highlighted but clicking it did nothing; now DrRacket seems wedged.

My CPU usage is pretty much 0, and memory has been stable too.  But
DrRacket won't respond to anything (and Windows has given it that pale
look it gives moribund applications).

Is there any way to unwedge it and retrieve work I had in it?  If not,
why might this have happened (where the Stop button does nothing) --
was it because it was making a system call?

Shriram