I thought I would throw my 2 cents into this discussion which will hopefully help some people out because I think I encountered most every problem there could be based upon many other threads on the internet.

The Situation: I have installed X plane 11.55 on my system. I had not used it in a while so I had an older version of the GTN 750 on my system. When I booted up X plane, my GTN 750 got stuck with the message "Rebooting" that never went away. Using a previous version on my machine of the "rpnGTN-XPL-Setup file I tried to reinstall that software. I was advised that there was an upgrade and chose to install it. That did nothing to fix my problem. I then tried to reinstall my software with the F1 Purchasing Module which is referred to as the "e commerce wrapper" above from RXP. I received an error that the server was being blocked by a firewall and would not allow me to continue.

After a good night sleep, I decided to start from scratch and reinstall both X Plane and the GTN 750 software using the same procedure described earlier. This time the GTN 750 did boot up, however, I did receive the same message as indicated by the comments of others above "Invalid License: Contact Vendor" message. Thanks to all of your instructions in this thread, I uninstalled Reality XP from "C:Program files (x86)" using the "unsins000 file" contained in that folder. I also deleted the "Reality XP folder" from "C:ProgramData" in the same directory. I then used the "e commerce wrapper" to reload the GTN software and this time I did not receive any errors and was successful in reinstalling the latest version.

Started the X Plane again and everything works. Lesson learned. Hope this helps and is plain enough language for those, like me, that are not that tech savvy.

Edited July 23, 20214 yr by RXP

Necroposting is frowned upon in there here parts!  I have split you off into your own topic!  Carry on!