Ive had the same issue.

I was riding to work today when the rear break felt odd. It went on then suddenly dipped and didnt appear to work. I pulled over ASAP and it appears that one of the break pads has lifted off and torn off.

Last october during the MOT there was evidence of the breaking surface lifting off and the breaks were stripped and rebuilt with new pads.

It seems that they are a little too tight. Attempting to order in a new caliper has resulted in the same issue. Yamaha only sell the brembo break as the whole unit and not as parts... thus my only option is to either spend �360 (quoted) on a whole new unit (which at this time is well over 10% the value of the whole bike) or have them take it all apart and reassemble it all so it can happen again in 6 months.

(ive had the bike since 05 and Ive done 11k miles)

what with the front fork wheel clamp breaking/shearing off during a tyre change last year as well (at a shop to the recomended torque) Im getting a bit miffed with it all.