I too had something similar happen, but the backlight wasn't just coming on the graphical buttons on the touchscreen were actually "pushing themselves". Apart from being freaky, it also had the benefit of locking out all hard buttons while it went on (and happenned on and off the cradle).

Long story short, URC tech support is great...we tried a few things on the phone and ultimately the unit had to go in for a new touchscreen. Just thought I'd throw that out there in case it helps.

RobA