Render is Double Speed

After moving to Snow Leopard (I believe that this is where it began) my renders have failed to work properly. They render out at double speed with the remaining 50% of footage as black. The same thing happens when I export to Quicktime Movie with "use current settings". Everything works fine when I export using HDV-1080i60. It's almost as if it thinks my footage is another format.

Can anyone help me? Is there any way I can set the codec for the renders?