I have seen a network user on a Managed Client logging in hang before the Finder and Dock load, so it just sits there with the desktop picture and only the Spotlight part of the menubar visible. The fix is simple. Delete these folders:
/System/Library/Caches/
/Library/Caches/
That should resolve the issue for the user whose login was hanging.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20060831191850908