"I updated my garmin 765T unit. New firmware (v4.50), new Maps (For example Garmin City Navigator Europa NTU Unl*** for 2013, 2014, 2015, 2016 as gmapsupp.img)..."
The maps for 765 are NT, not NTU.
765 is very old devise, defragment it ( make backup of internal memory, format it ( FAT32 ) and restore).
Remember that the presence of a large number of unused POI may cause undesired operation.