after my tivoHD rec'd the new 9.1 update, some channels are displaying only as a gray screen. is this a known issue? i tried reinitializing both cards, but it still does this on one tuner. i'm not sure if its one cc that is causing this, or tivo s/w or a combination. i dont want to call for a tech visit until i know what i'm dealing with. they told me if the repair wasnt a cable issue, i' would be charged, as i'm sure this is standard operating procedure.