I'm kinda in the same boat as you are and it's driving me nuts. My uke is starting to rattle after my new worth clears began to settle, more specifically my c-string when played on each of the first five frets. Thanks to Dino's post, I found that it was the string touching another fret. So I raised the saddle and the rattling/buzzing went away; however, the action now is so freaking high. I'm not quite sure what to do now. The only thing I can think of, without keeping the incredibly high action or sanding down my frets, is to get another set of strings that won't bounce around as much. Probably a set with high tension, maybe d'addarios.