[edited from a related support email exchange involving similar issue as reported above]

Empirisoft Support Wrote:
There were a handful of issues with DirectRT 2008.2 and DirectRT 2010.2 that resulted in some strange program behavior on some system configurations. Most of these issues were resolved with the release of v2010.3 and again with v2012.4 (posted March 1st, 2012). Any chance you could try installing one of these versions to see if it can resolve the input file opening problem you are experiencing?
User Responded:
Thanks! The update seems to have done the trick