Premiere CS3 Mac will not export HD mpg

[Chad Huntley]

I'm using the Adobe Media Encoder in Premiere to export my project. Whenever I export with MPEG-2, using any of the preset settings in the list, it produces a video file that "Is not a movie file". I've tried moving the movie.mpg file to another machine, and it wouldn't play it there either.

Also, after I use the Adobe Media Encoder and export the file, if I try doing it again, Premiere freezes.

Figures the very last step would be the one with the most problems...