Similair thing just happened to me after upgrading this evening (FL12020023) but I rotated to right portrait, things seemed OK, then left portrait (so the power wire would be at the top). After that the screen locked. Powered down for a minute and it came up in landscape mode however when clicked Navigation the screen locked with words (in landscape) saying "loading data and..." with a vertical white bar several mm across about a third of the way from the left of the screen. Thanks to the great advice of the initial poster I succesfully got back to landscape mode by taping the lower left hand corner (unit orriented in portrate mode) then selecting landscape mode in a partial overlaping menu. Like the portrait mode (and the 720 in general) but will also be waiting for some bug fixes before try again.