I am not 100% on this one and don't really want to take my live system down again to test but.......
RC14 installed on two RB333's. Ping watchdog tickbox set to off in winbox and double checked in terminal to show off. However the IP address to ping WAS filled in. I think this may be where the problem lies. So Normis et al, you might want to check what happens if the IP field is filled in but the tickbox is not set.