Ive been working on an illustrator comp in AE CS3 with no problems until i increased the project length past one frame. I interpreted the footage to loop so i could animate with it, only to find that AE is playing a file that i never once imported, every other frame. Its those colored tv bars with a black sign in the upper left with the name of a pdf file that was sitting in the same folder as my comp. Not only that but its playing extremely slow.
I removed the offending pdf, created a new project and brought the original illustrator comp in to see if it would still appear and its gone, but now i have no way i getting my project back and no idea if this is going to happen again.
Sounds like you may have imported the Illustrator document and the PDF as an image sequence, rather than as individual images. Did they have sequential names?
In your original (problematic) comp, replace the original file with the Illustrator document, but ensure the "Image Sequence" checkbox is not checked in the import dialog box.
That did it, thanks!