I've had it happen. Sometimes I can play for hours without it happening, but it also happened SIX times in a row. Very aggravating. It almost always happens playing keys, but it happened once with guitar.
Try Need You Tonight, Rainbow in the Dark, or Just Like Heaven on expert pro-keys. Once you beat them (and you can) you'll feel that much better about pro-keys.
You can get fans by completing the specific instrument and band goals, eg getting 100% on a guitar song on expert or 5-starring 25 RB3 songs. Look under Career, then My Goals for easy goals.