I select the two exposures I capture using the TruHDR app on my iphone or three Canon raw files / exposures I capture with my Rebel T1i. Select Photomatix plugin first to merge and tonemapped the exposures making a new version. Then I select topaz plugin adjust for that image, use my preset then click ok. Next I use the topaz plugin detail to do my final sharping of the image, click ok. Most of the time I have no problem till this point but a few times the problem will show up after using the photomatix plugin before the topaz plugins, Most of the time the problem shows up when I select export version from the menu. I choose the location I wish to save/export the image too, then click the export versions button, a box pops up saying file save with errors and I get a black image saying unsupported file error.
I had the same problem with the Photomatix plug-in and this solved it for me. I realised it only happened with Photomatix and not other plug-ins so I checked where the plug-ins were installed. The Photomatix plug-in was installed in
where ~ is the home location for the current user account. All the other plug-ins however were installed in
Macintosh HD/Library/Application Support/Aperture/Plug-Ins/
which is the location that makes them available to all user accounts on your Mac. Moving the Photomatix plug-in to this location solved the problem for me.
Note that the Library directory under the first location is normally hidden, to get to it hold down the Option (Alt) key and select it from the Finder Go menu.