I just installed the Garmin Mobile PC 5.00.70 update. I was a bit hesitant to do the update, as my two earlier version updates resulted in the software not starting. This time around, however, I've experienced no such issues. The program started just fine after the installation completed. It actually appears to start a bit faster, but this may just be my subjective and incorrect observation.
One negative thing I noticed is a missing keyboard shortcut that I use very often, the Enter-key; it no longer switches from the navigation mode to the "Browse map" screen. I need to tap (or click) the small "Browse map" button in the bottom left corner of the map instead. Too bad, 71 items fixed, one item broken.