This is a shot in the dark but I’m wondering if deleting or renaming some files for a clean install might help. The following is about how to revert versions but he talks about the .sender_rc file a bit. I would also check the AppData hidden folder. I can’t remember if gSender’s folder is in C:\AppData or C:\Users\your name\AppData but there should be a folder somewhere in there. You can rename that folder and .sender_rc before installing gSender.
It’s worth a shot… You can export your gSender settings first to aid in setting up the new install.