I found this worked for me somehow I corrupted the .kde directory s deleted and rerun kdm an all was well again.
hope this helps someone.
Thats the sledgehammer method I use too if gnome has some startup problem -> rm -rf ~./gnome*
will list files in your home drive that start with a ., e.g.
this is where the configuration file get stored for most of the programs that you've started. if you delete the folder or file it will get recreated with the default settings the next time you start the program.
that's strange, kdm doesn't store any files in .kde, so i don't think deleting .kde is a good idea for this, and please don't suggest to delete complete dirs, moving is much better, then you can copy other config's back.