OK... I think I figured out what I did to hose this up, AND, I think I fixed it.
When TT Home popped up last night, I inadvertently selected the SD MEMORY CARD, rather than the INTERNAL memory, as my active device. This occurred because the internal memory was assigned N: by my pooter, andit assigned M: to the SD card. I thought, in my haste, that the "lowest" letter (i.e. M: ) MUST be the Internal Memory.... WRONG!
I then allowed it to update the software version --- which it DID, only it did it to the SD card....
THEN, I realized the problem, reconnected to the INTERNAL, and reinstalled the software update. SOmehow, it appears that this set the software up such that it believed that GUAM was the only map --- which makes sense, as I only moved the NA map to the SD card when I moved maps some time back. I did NOT move the Guam map. It remained on the Internal Memory.
What I did this morning is, I looked at my Explorer backups, and deleted everything off of the SD card, except for the folders that appeared in my previous explorer backup of the SD card.
I then changed to internal memory as the device, and added the 830 map, which was still on my computer.
Once THAT was complete, I moved (via explorer) the NA Map folder to the SD card via explorer.
When I pulled my device off the cradle, and fired it up, it asked which map I wanted, I chose NA (which is only on the SD card) and it worked.
It seems that I am now back in business.
Only thing, I can't remember how to restore my previous favorites from my old explorer backup to the TT. I'll have to look thru my previous posts to remember how to do that. I remember that it wasn't too hard.
There must be a folder/file somewhere in internal memory that flags that the NA map is on the SD card, and directs the TT to look THERE --- AND it got killed when I went thru the OS mess-up.
I THINK I am back in business minus my favorites, which is probably an easy fix with explorer back-ups.
ALWAYS ALWAYS MAKE EXPLORER BACK-UPS. If I hadn't had those, I would have never been able to track this down.