I can't guarantee this is going to work but try this: find out how many libgimp-2.0-0.dll files you have in GIMP Program directory. In GIMP 2.8.x it should be two of them in bin and 32/bin folders. If there is more than two, delete extra one(s) and see if this helps. P.S. Admittedly, 64-bit precompiled C plugins work faster than 32 in 64-bit systems. So I would stick with 64 plugin version.