unfortunately, I have to return to a topic that has already been discussed. Working on MacOS Lion with RM 5.2.003 and PaREn 5.1.001, I am facing the same problem like siamak_want in thread http://rapid-i.com/rapidforum/index.php/topic,4777.msg17296.html#msg17296
when you run the PaREn, you will see an empty "Error" dialog box with just a close button. And the PaREn does not work at all. If you press the close button, PaREEn will be closed!!!
cbwg has reported this behavior as a bug http://bugs.rapid-i.com/show_bug.cgi?id=1063
that, then again, is a duplicate of the solved bug http://bugs.rapid-i.com/show_bug.cgi?id=1056
I downloaded RM 5.1.017. PaREn 5.1.001 works fine with this old version. It seems that the bug has not been fixed or the bug did not cause the problem.
I am thankful for any comments.