2.6 is what broke it. 2.5 has always worked as well as the betas of 2.6. But I installed 2.6 over a 2.5 installed machine and once it tried to uninstall 2.5, it broke it.
I did everything to remove all traces of 2.5 or 2.6. I then installed the FULL 2.6 with .NET included. Same problem.
There's something really wrong with either the 2.5 or 2.6. I'm afraid to try installing it on any other machines as I use Paint .net quite a bit.
I no longer have a working copy of Paint .net on my main machine and am dying to get this resolved!
-Mc