Well I have tried different costumes (pcs&pac) over the white slot, but to no avail.
that sounds like corruption if any hack over the white costume is messing up, how do u load ur hacks? if it's thru a usb loader or emulator u can try downloading the original files for DK to see if it helps. or if ur using gecko or riivo u can try to remove ALL of the hacks on DK to determine if it's an issue with what u have on him.