Collectible Card Game Headquarters

I continually get a "Couldn't Save Preferences" error in the client. It happens when I switch to the deck editor screen, try to start a game, and will completely crash the application if I try to actually go into preferences, make any change, and hit the save button. The error is noted in the mageclient log file as such:

ERROR 2016-03-28 10:55:45,506 Error: couldn't save preferences
=>[AWT-EventQueue-0] PreferencesDialog.saveButtonActionPerformed

I have yet to find any mention of this error either here or on the Xmage Reddit, so troubleshooting has been nearly impossible. Any help would be appreciated.