Writing the melody in my head

[djones]

What happens to me is, whenever I have something going in my head and want to translate in into some music.
As soon as I hit a note, or just play any sound, this will totally affect what I had in my head.
And it usually wipes what I've had in my head as well.
If I could just write everything down what I'm 'hearing' in my brains, I'd be another Mozart for sure.