[Therion] Therion 5.3.16 - Error opening th and th2 files

Hello everyone - I installed therion 5.3.16 a week ago but never did anything more than verify it would start. Now I need to do some work on a map. In xtherion - Whenever I try to open either a th or th2 file (text editor or map editor windows), it throws an error. I took a screen shot and attached to this message. The error comes up as soon as I click on the File-Open icon. It never presents a file chooser dialog. The cave will compile correctly. The thconfig file opens without error. This all worked in 5.3.15. The system is 64-bit Fedora 21. Any ideas? Thanks - Bill Gee