All video formats say "invalid"

I have a project to score a short video. I’ve done this before, but in an older version of Cubase. I have tried every video format I can possibly export from my video tool (Magix), but all report invalid by Cubase 6.5, and will not load.

The original file is in Quicktime, and is very large - will not load. I tried making a smaller .mov file - will not load. I tried mpeg-2, avi, uncompressed avi, in various sizes and frame rates - none will load.

Note: All videos play in Media Player or Quicktime player fine!

My system is a quad-core desktop running Cubase 6.5. *Edit: I have also tried the same process now on my other system, an I7 laptop running the 64bit edition of Cubase, and also tried converting the video using other tools. still no luck.

I am under the gun to get this production out the door, so any suggestions would be great.

(And yes, I read the kb article on video, and checked the specs on the product web site)