Hi Klaus,
I just checked the group rights on your wiki and it seems that there is a
error there, nobody has the right to edit pages.
This can be fixed by adding the next line to your localsettings.php in your
mediawiki root.
$wgGroupPermissions['*']['edit'] = true;
You could check
http://www.mediawiki.org/wiki/Manual:User_rights also, it
seems that you're missing the rights for admins, crats, etc etc also.
Best regards,
Huib
--
"The soldiers graves are great preachers of peace...."
http://commons.wikimedia.org/wiki/User:Abigor