d-pad not working on games or home page

morning all my psp has semi frozen as in all the games load but when i want to select a menu by pressing up or down nothing happens. also when i press home and it says do you want to quit game i cannot select yes because the d-pad wont shift the cursor to yes it stays on no. have rebooted and changed games and can play the games as long as i select the top option as i cannot scroll down. was playing pinball last night absolutely fine turned it on this morning for a quick bash before work and no joy. anyone got any ideas or has this happened to anyone else. have also changed memory card and taken battery out but still no joy.