One possible alternative is that I don't have the tangled lips/hands thing when I'm playing my own stuff, I guess because a: I wrote it and I know how I want it to sound, and b: I'm really not trying to sound like or be in tempo like anyone else.
Ah, that is great advice and is exactly how I'm doing it. I bought an acoustic guitar a few weeks ago, and aside from always wanting my own acoustic guitar, I was dying to learn to sing and play at the same time. An ominous, if not hopeless task at first, though.
Playing some other artist's song was just not cutting it, and almost all of my original material had been multitracked. To make things worse, it was all weighted in a way that made impossible to play and sing at the same time.
So what I did was write a simple simple little song with a couple chords in it. I played that dumb f**ing thing for two hours a day for three days. I'm sure any neighbors that walked by were laughing their asses off. Eventually I was able to play for three minutes or so while singing an easy little rhyme.
I know it falls in the line of "practice a lot", but I think we need to keep in mind that you have to practice right. Just because you are sitting behind your guitar for several hours a day, it may not help you at all if basic technique is not being adhered to. And trying to start with a cool Zakk Wylde acoustic piece ain't really the smartest thing to do, either.
I saw where "Jim make funny joke" earlier in his thread, but I'll have to say he made a lot of sense - Peanuts make the elephant big. Ah one and a two... Not always what should be done, but definitely worth a try when trying to coordinate dexterity and motor skills.