just delete de.u from unrealtournament/system
on the laptop go into unrealtournament/system/unrealtournament.ini and search for serverpackages=de put ; infront of it so it looks like this ;serverpackages=de
then save. start the server up and join it with the other machine. it should be ok now. no one uses de.u that i know of but should you decide to keep it for some strange reason.
leave the laptop alone without the above fix. on your client machine "the one u use to connect to the laptop /server" go into your systemfolder and delete de.u if its present. also open your cache folder up and look in the ini thats in there. if you find de.u look for the guid"those numbers letters @ the start" find the file it belongs to then delete it and remove the entry from the ini. save.
all done
no idea if this has been answered elswhere and i know im a little late replying but what the hell