Hi,
I've just tried opening a bunch of files for HDR merge and as soon as I try merging them AP crashes with the same error.
I'm adding 5 16bpp TIFF files that were extracted from Canon 7D RAWs with multiple exposure settings (around -2/-1/0/+1/+2 eV).
I'm having no problems with opening these files separately (or for stacking for that matter).
I could provide you with the files, but not via public channel.