NAVMAN S50 Screen Freeze

Question

My S50 often (about once every 3 or 4 trips) screen freezes so that the directions and instructions still are heard and the distances etc are still shown but the moving boomerang icon disappears and the street view stays at one that was previous. Fixes with a few touches of the screen but this is a distraction. I have downloaded and installed the faster recalc fix for Australian only NAVMANs and that is brilliant!