Now going back to the original problem on my PC: I used a video converter to try out different file types on After Effects that would not produce an error. I found that MPEG-1 and MPEG-2 worked fine on my PC and MAC. So, if I need to cross over again, I know NOW to just use this format (container).
MPEG-1 and MPEG-2 are lossy and compressed (not to mention, old) formats. They are not appropriate as intermediate codecs! At all! Never were! Not only are they compressed, but they use interframe compression which is not ideal for After Effects.
Use DNxHD (from Avid), Cineform (from GoPro), Quicktime with the PNG codec, or Quicktime with the Photo-JPEG codec. Any of these work just fine in After Effects on Windows and Mac and aren't lossy.
Thanks Szalam. I was only trying to help and the limited converter software I was currently using only converts to certain file types. I just loaded MPEG Streamclip and the Avid codecs. Please advise if there are better apps to use. Thanks for your help.
After Effects, Premiere Pro... Adobe Media Encoder are all way better than MPEG Streamclip.
BTW, a PC can use Quicktimes just fine, just pick a frame based easy to decode codec like Jpeg 2000 or PhotoJpeg and you are good to go.
The video camera's original format was MPEG. (I converted the files to .MOV, thinking it would be more compatible since After Effects works in tandem with Quicktime.)
This was likely the initial problem. MOV is just a container and whatever codec you used inside your MOV container caused the problems. Newer versions of AE (usually) work reasonably well with MPEG files, but if you do want to transcode them into a proper production codec, use Adobe Media Encoder to go to one of the formats Rick or I mentioned (note that most of them are MOV files, just with different codecs inside).