Hi Roland,
This is a configuration bug in the CKeditor, it is html encoding the special characters like this: like ä, ö or ü and the characters go into the database that way and this causes also the content to not be indexed correctly.
I jut fixed this in my copy so it will be fixed in the next release.
In the mean time you can use TinyMCE or FCKeditor and then new content you create will not be encoded. You may need to manually fix content that is already affected.
Hope it helps,
Joe