Why is my iPod going CRAZY?? (or possibly iTunes)?

[funkeeemonkee]

My iPod won't let me put anything on it! For some reason I have to sync everything, like the music, I had to put all in a play list in iTunes and tell my iPod to sync the play list... I have no idea what is going on with it, but every time I try to put a song or video on it, it has the little cross thingy that is does on iTunes when you can't do something.... It's really confusing, and it's driving me crazy! PLEASE HELP ME!!!!