Dear James:
It is possible that you are using a complex directory path for RMS or your drawing files. This might be causing RMS not to be able to load the ARX file. Perhaps you can try a simpler directory path.
Otherwise, it sounds as if one of the RMS files is corrupted and I would recommend reinstalling the RMS software.
Hope that this helps.
Sincerely,
Chris E. Maeder, M.S.
Senior Technical Engineer
chris.maeder@bossintl.com