Failsafes to prevent possible errors on forced system shutdown

PD assumes that it will be able to nicely unload itself via natural
methods, but when a system is forcibly logged off, things change and PD
was throwing unpredictable errors.

I tracked the problem to two potential places, which have now been
solved.  Forced shutdowns shouldn't be a problem.
Fix initial position setting of image tabstrip on fresh install

Dumb mistake on my part - apologies to anyone who's downloaded a fresh
copy of PD in the past few days, as the image tabstrip will be
completely botched.  The "set default position" code wasn't firing on
new installs, so the tabstrip failed to ever be aligned properly,
meaning it was never being rendered!