I got the same error yesterday on my office computer (with multiAVCHD, trying to load the plugin). I believe it is compiled for certain CPU (OS?!)
Works fine on my laptop Vista 32bit Intel PC, but fails with my desktop office XP SP2 Intel PC. Both with Core2Duo CPUs.
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Thinking about it, I'll try to install .NET on my office PC and will test again tomorrow. It may be .NET compiled (the .dll).