Hi Josh -

Is this problem limited to that one file, or do you get the same error replacing "Ref.nrrd" with a different file name?

Also, things to try:

- use ".\Ref.nrrd" (Not sure this makes sense in Windows, but always a good thing to try on Linux)

- use full path to file, e.g., "c:\Data\My Files\Ref.nrrd"

Finally, my standard recommendation for Windows users - consider switching to the Cygwin version of CMTK, since it is more optimized than the Windows binaries. I built the latter with the free MS compilers (thus without OpenMP), resulting in very limited multi-processor support.

Best,
  Torsten