Chimp, have you re-installed the game completely lately? Sometimes when I've done that for some reason I've ended up with some files that end up "read only" which would make things like the terrains impossible to update. Unchecking the read only box usually fixes that unable to update terrains problem.
I just do a right click on the ah2 folder click properties and if the read only box is checked I uncheck it.
I seem to remember a thread saying something like installing the game from a downloaded CD will make some things check read only. Not a techie by any stretch.
Drano