cdj 900 e-83 02 code

hi, i've recently been having trouble with my cdj's, they every now and again cut out and the screen come up with E-83 02 ............ i havn't connected my cdj's up to rekord box, or any other vitrual mixing software, i only use usb stick and cd's, does any one know how to over come this problem as it's becoming embarrassing when i'm playing out and the music just cuts

thanks, stephen