I can't say for sure that this is the answer, but it's worth a try...
Browse to the C:\Documents and Settings\user.name\Local Settings\Application Data\Bentley\MicroStation\8.xx\randomcharactershere\prefs folder, and remame the file GC.docking.xml. Now restart GC. Any difference? If not, go back to that location and rename GC.upf as well.
HTH