There is a sound issue on some 4500s which affects a few channels You can pm allaboutbuzz with your box info and a fix can be sent if that is the issue
Any more information to post that might help?
Are all tvs the same?
what are your hdmi/cec settings?
what home screen you using?
are boxes being powered off or sleep mode?
Insert a USB stick Format stick with buzz then go to pvr settings and change storage location to your USB
See if it will record.
Would you also post what version of buzz 5 located at bottom of screen when you press menu