accessing localhost from outside problem

Dear all,

while accessing the example site from the last version of MODX I came across one problem.
the requested URL is changed to localhost . So the site works locally but not if I access it
from outside via a domain name.
Is it a known problem and how to make MODX persistently use the requested URL?

Thank you in advance for any tips.

Kind regards
Maxim

Web Server: APACHE 2
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PHP version 5.x
MySQL version ?? seems to be not important for this problem
Operating System and version XP

Is this a pre-configured server package like XAMPP or other?

-sD-
Dr. Scotty Delicious, Scientist.