Appreciate any help!
The best option for encoding H2 64 is not to do it directly from inside AE. H264 responds best to multipass compression. I would render out your files to a lossless or nearly lossless codec like animation QuickTime. You should also check the Wikipedia page for some great reference material on H264.
I was exporting h.264 files fine, but suddenly it gave me the error thing. Don't think I changed anything for that to happen.
If I export animation QuickTime won't that make huge file size's?
Will check that Wikipedia page.
The Animation Codec file will be huge, but the H264 you make from it will be higher quality and even smaller if you use some good multipass rendering options.
You could have missed a critical frame size, or a bunch of other things that caused AE's render engine to fail.