Update: So now I'm able to actually add m4a files to my playlists, but they sound like the Chipmunks. LOL! But at least I'm getting somewhere. The thing I was missing on how to be able to get uLilith to recognize the m4a was this (thanks to Northern Verse!!): He also told me to download and install Haali Media Splitter and ffdshow, but since I already had those installed, I skipped those.
What I've done, is open the playlist, and either dragged over a m4a file or chose "Add". I can see the file(s) when I choose "all files", but it doesn't actually add the file(s) to the playlist. Are you able to play m4a files?
Ughh... I'm sorry, I meant m4a not mp4. I checked the file operations menu, and m4a is listed there, but it still will not add m4a files to a playlist. And I have the CCC Pack installed. Is that good enuff, or do I have to specifically install the K-Lite codec pack? And I got a i7 processor. Which uLilith should I be using? Thanks again for all your help!!