Downloaded and installed the latest archive marked for 2014-03-25. How to reproduce:
Open the program. In the graphical menu of the program, if you select the option "Remember last directory". Close the program. If that path changes (such as the directory is deleted), GPRename will no load next time. It gives no message to the user (except on the STDOUT of the console).
My suggestion is have it default back to a user's /home/USERNAME directory when it cannot find the last directory.