Hmm. The snag with MediaLab launching DirectRT was a known issue with DirectRT (not with MediaLab) in the later releases of DirectRT v2010 and should be fixed in DirectRT v2012. Can you double check that the version you are running is recent? i.e., (2012.4.x or later). If it is, can you double check that there is no second installation of DirectRT on the machine? You can do that by searching the hard drive for "executedrt.exe" which is the main executable. It's that file that should be version 2012.4 or later. See also the following related link:

http://www.empirisoft.com/support/showthread.php?t=532

Hope that helps