I got the unit for an early Christmas present and installed it a few weeks ago. I did the upgrade on the firmware to 5.84. It did fine the first time out. I have a 12VDC power supply so I have been powering it up in the house and loading in waypoints I had saved in my old GPS by typing them into Humminbird PC. Everything was fine after I added everything. I used the new waypoint management feature, made a folder for each lake put waypoints in the folders, then I started deleting waypoints that were in the main waypoint folder in the unit and it locked up. After powering it down it locks up on random screens (that have map data, or screen shots, imaging screens are fine). I put it on the boat, no difference. I've tried restoring defaults, reloading the firmware update (it won't take it because it is already ver 5.84), not using a SD card, etc. It almost seems like the base map is gone? Any suggestions?