I have de-installed avisynth, removed all additional plugins, rebooted, and re-installed avisynth 2.6.0. Still the same problem.
Windows shows me a debug message offering to send 3 files to M$. I have refused, but I have kept the files. If they can be useful to help diagnose the problem, you can download them
here.
Don't spend too mych time on this problem. If it is confirmed that the crash occurs only on my PC, I will distribute the new FRIMSource with the next version of BD3D2MK3D, and I will use DGMVCDecode personally. Thanks anyway for your patience!