MFPs are signatures on the management frames of the access point. This message means there has been errors in the signing of some messages from neighbor APs.
This can either mean an attack (someone trying to spoof your AP), but most likely it's one of the few bugs on the topic that are hitting the WLC.
This got partly resolved on the current 7.0 code and will be completely fixed in the next 7.0.
Nothing to be alarmed about, it's a notification.
Nicolas