System.BadImageFormatException: Could not load file or assembly 'Accessibility, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' or one of its dependencies. The module was expected to contain an assembly manifest.
Looks like there's a file called "Accessibility" somewhere in your Paint.NET folder that got messed up or something. (I program in Java, not C#, so I'm not sure but I think that's the problem.) Copy this:
C:\Arquivos de programas\Paint.NET\
Press Windows, and then press CTRL+V. If you see a file called Accessibility, then that's a problem.
Also, I hate bacon.