In Explorer, in the Folder options menu (that's where you may set the "Show hidden files and folders" option), there's another option - "Hide extension for known file types". Because .ini is known file type (it's associated with Notepad), you could try to uncheck this option and than you should see the whole file name with its extension.
If this doesn't help you than I'm out of ideas...

edit: One last thing you can try is to uninstall the game, delete the game directory and install it again. Then when running LF3 for the first time after installation you will get the choice of enable/disable mouse once again.