Problem(s) Encountered:

Everything ran normally for the first target (a standard star) but partway through the first science exposure, Prospero locked up — it stopped updating the countdown, and did not respond at all to typed commands (even ctrl-c).  Just nothing.

I contacted Eric, and he resolved the problem by logging on remotely (Yay! We have fiber!), doing a ps -aux, killing any processes with Prospero  in its name, and restarting Prospero.

And, voila, it was solved!  After resetting the camfocus, it was almost as if nothing had happened, though of course I lost that one exposure.  

Solution:

See above.