Not sure if this is help or hindrance but:
When we changed back to the Simbin Lobby, I couldn't get in or register with my old profile name. So, I re-registered with a new on-line name (Used wad63 instead of wad53) entered my normal on-line code and it accepted it fine.
So maybe you are able to register with a new name for your new Jack Smith profile which seemed to work (based on what you posted back a few hours).
Since you are still trying to use and older profile and still having problems, maybe worth trying to delete the files in the Hat Folder and the Results Folder. It will create new ones when you next drive them.
If all else fails, I'd be inclined to clean everything out, and re-install GTL and create new Profiles etc, then slowly introduce the mods needed to your plr file to get everything as you want. Same for any old setups etc.
Whenever I have these sorts of problems, I always find it quicker (and safer) in the long run to completely start anew.
Just my tiny but very conservative thoughts if you are getting nowhere.
I assume you have checked your PC for viruses?