All of these programs run on the Microsoft .NET platform. It is quite possible that your installation of it is broken in some way. Please try following the directions in this article to repair it and other system files:
http://blogs.msdn.com/b/astebner/archive/2007/03/26/how-to-repair-the-net-framework-2-0-and-3-0-on-windows-vista.aspx
Another possibility is that other software on your computer is incompatible with DirectSkin. To test this, try renaming the "wbocx32.ocx" file in the TweakVista directory, and start the program. If it runs without it, I suggest putting it back and temporarily closing/unloading other software running on your computer, then trying to run TweakVista and seeing if that fixes the problem. (If so, we need to talk to whoever makes that software.)