Do you have an eq2.ini file in your base EQ2 directory? And does it point to the proper folder? It should look similar to:
cl_ui_skinname
thorui
cl_ui_subdir UI/
You may also want to check out the last post on this thread:
http://www.eq2interface.com/forums/showthread.php?t=293 (which also contains the info on the eq2.ini file mentioned above
).