halo reach set up problems

hi there am completely new to thses games , but thought after having an xbox for so long id give them a bash, so bought reach. However the problem im having is that it wont save, autosave or manual, soon as i turn it on its saying cannot save content or something and keeps popping this message up every few mins while i play then when i played again it was back to the beginning ! it also says my hard drive or xbox memory whatever may have been disconnected but it isnt i can put black ops in straight after and it loads up even checked in system settings and ive got loads of memory left ? jusy wondered if this is a common falt or something i need to do in some setting ??