I have the same issues running AE 8.0.2.27 under Windows xp pro. I cannot import h.264 files either. If you select QuickTime Movie as your Output type and select H.264 as your compression scheme, you can avoid the roadblock you describe. The file ends up with a .MOV extension but you can import it unless you change the extension to mp4. It’s not elegant and I’m not sure if the file sizes would be the same. AE 8.0.2 was supposed to have fixed this. Anybody have any ideas?