I've been getting this error after I installed AE on a fresh installation of Windows. Google has a collection of complicated explanations. Mylenium has a nice blog about error messages, but it also has a big explanation.
So I stated thinking: Fresh install... codecs! What am I using? I disabled all mp4 layers and the error went away.
So if you're getting 17 :: 19, you might want to check for something simple like Advanced Video Codec footage without Quictime, FFDshow or Core installed.