Sussanb, Thanks for the quick reply. I rung them a couple of days ago, Australia Garmin from New Zealand, very nice people but said that it was probably a win10 problem and said they could not do anything about it. Now a couple of days later I am more than a little hacked off. BaseCamp is made to run on Windows. My system was running on Win10 just fine. I have uninstalled it twice now and installed a fresh new copy of BaseCamp. It does not run. I expect it to run, how else am I to use my (2nd) Montana GPS?