Denso TP-RC5-1 pendant problem

Hi. I hope someone can help me with the problem that I am having with my Denso RC5 controller with TP-rc5-1 teach pendant. After powering up my robot controller, the pendant will not go into the graphic interface. The blue screen displays a message saying that I have a 'Bad boot sector or non DOS disk. Program aborted'. Can someone help me out? Any help or advice will be highly appreciated. Thank you.