Hm... never worked with web-console of Firefox so far. Entered the mentioned value, nothing happened.
BUT... after I was finally able to login into the manager at the new location and removing the "base href"-entry, I was able to re-run setup, updating the modx-installation and: now it works!
Thanks a lot for your patience (both of you), I really appreciate the helpful atmosphere in this forum (and btw... thanks for your book, Bob, which I bought before starting to get involved with modx).
Now I'm in the mood to get the real move/relocation getting done...
Well - there isn't "the" answer which solved all (and thus to be flagged as answer - I will flag one answer anyway to mark this thread as "solved"), but the sum of your answers got my thoughts running in the right direction!
I'm glad you got it sorted.