Any MP4 or one MP4 in particular? What about PNG sequences, MOV files, and JPEGS?
What, exact version number of AE? Is it 13.6.1?
Where did this MP4 come from?
When you say, "force quit", what do you mean? That's a Mac OS term and I can think of a couple of different things you might be doing in Windows that you could call "force quitting".
Have you ever installed a third-party codec pack, such as K-Lite? I've seen them cause issues like this in the past.
I thought it was one MP4 from a Dvd that came with a book about AE. I tried other MP4 files from the Dvd and they worked. Just tried again and i think my Dvd drive is broken, i no longer hear the spin up of any disk and the file explorer is not responding. I guess to answer your other questions.
Im Running AE Ver 184.108.40.206
By force quit i ment End Task through the Task Manger.
Codec Pack? I have Quick Time and Main Concept.
Got it, i did dvd in laptop to USB drive to Computer with AE and now it works.
Hooray! I'm glad it's working.