I got this error today, I had rendered a quicktime movie (a test, using the save as command in the picture viewer) from Cinema 4D and inadvertently saved it as a still, but with a .mov extension. As soon as I realized my error I resaved the file in C4D and when I clicked reload footage in AE, I got the error.
The footage lost its icon in the project window and appeared as missing, if I could I would have removed it from the project manager and reimported it again, but the strange situation message kept popping and I had to force quit.