[SixOfSpades]

Then that's . . . just bizarre. Tell us, what exactly does happen when you try to do the precise steps I listed?

The first thing you should try is to start a new game, and see if your country travel is prohibited in that one, too. As for your current game, all I can suggest (at least for now) is to cheat yourself to the desired locations. Open up your Baldur.ini file, look where it says "Program Options" and "Game Options, and add the lines
Debug Mode=1
CheatKeys=1
below each of them. (Actually, you only need to enter each of those lines once, but I forget which one of them goes where, so I just do both.) Then, when you're in the game, you can use the CLUA console.
Save the game before you cheat, especially when you're attempting something this big.
In the game, press Ctrl-Space. This opens a bar at the bottom of the screen, where you can type commands. Type CLUAConsole:MoveToArea("AR1234"), where 1234 is the number code of the area you wish to teleport to. I actually know hardly any of the area codes, sorry to disappoint, you'll just have to use trial & error, but almost all of the big, main areas (the ones that appear on the World Map) have numbers that end in 00, for example the Docks District is AR0300. Note: When using the CLUA console, capitalization is very important.
Once you know the number of the place you want to go, Reload to before you began your wild teleporting spree, Pause the game, make sure your entire party is selected, and CLUA yourself to your desired map. This will place you as close to the top left-hand corner as the map will allow, which is not always where you're supposed to arrive--for example, when you enter the Druid Grove, you always do so at the bottom right. So, before you un-Pause, put your mouse pointer as close as possible to where you think your party should have showed up, and press Ctrl-J. This is a clumsy, ugly fix, but it'll work.