Thanks for responding. I knew I'm not the only one with this problem.
As I believe that I have previously stated, I have tried doing that but it did NOT fix the problem. I have even tried that proposed solution multiple times now but have still been unsuccessful in resolving the problem. I also wouldn't exactly call it harmless. It should definitely be fixed of course.
So far, it appears the problem only exists with Minecraft versions 1.8.2, 1.8.3, and current latest 1.8.4. At least, for me.
The text error seems to no longer appear though. However, the minecraft jar still shows as that "a/io/File;)Z" for those particular Minecraft versions when choosing that Minecraft version's environment.