I researched your question over the weekend and could find nothing to support black-n-white REPLAYS? The screen is not Blk/Wht while you're playing? If it's only happening on REPLAYS, I'd try another TV if you have one. If it still persists, maybe it's the unit, playstation. My options-menu have NO WAY to make replays black & white. Call on Mr. Sparkle for help. He's pretty good.
"You don't know what you know until you know what you don't know".
'TeemByrd'