Boulder: Somehow the line breaks were converted to UNIX-style recently. I've updated
the OP to use Windows style line breaks again so it should be more readable now (no version number change). I use Notepad++, Visual Studio or AvsPmod to edit, but those editors will accept any line break style so I didn't notice the problem.
Delerue: You cannot always run 1 thread per core because you might run out of memory. On 32-bit avisynth you have 2Gb memory regardless of your machine. Multi-threaded complex HD scripts need more memory (which is why we need 64-bit Avisynth). Cut down the number of threads. Also always try different versions of MT avisynth. Just because MVTools works for you multi-threaded, doesn't mean that you are using the most stable MT version for your machine.
nhope: I'm going to add plugin packages for 2.5x, 2.6x and x64-2.5x to the OP to ease the plugin confusion. I'm not in my lair at the moment so I can't test anything properly - it will have to wait.