Try doing a master reset of the phone to restore the factory default settings. Make sure you back up any data first (including your address book) before trying this.
I have a hand me down Palm 700w. I use the Verizon wireless service. My phone doesn't ring when someone calls me unless I happen to be doing something with it and the screen is lit up. I can't figure out how to fix this problem. Is it a defect in the phone, or me?