Unresolved Minecraft Save Error...

Hi Peoples...
Whenever I open my world save in the minecraft tab and try and save it, I get this error...

And when i drag and drop it in and press mod file, this is what appears...

 

One thing. I've tried this with multiple saves, my own and some others i've downloaded. It just keeps coming up with the same error...

 

First of all, please refer to this thread for any further minecraft problems.. http://www.xpgamesaves.com/topic/40204-common-minecraft-problems-solutions/

Secondly.. Download this.. http://adf.ly/9YkZ4, and then open the .exe file.. drag your gamesave into it and then MOD File.. please posts results.. AND a copy of your save uploaded at www.2shared.com