> I've only heard of that type of thing with 3D PDF.
> I would be surprised if PowerPoint was able to view CAD files in 3D.
Powerpoint itself can't display either JT data or 3D PDF data -- but it is able to delegate this job to other software. Since JT2Go gets launched when you double-click on the image in Powerpoint, the linking/embedding must be working, basically. If things don't work in slideshow mode, I'd guess that some Powerpoint parameter somewhere needs to be tweaked.