Short answer, you're out of luck until Comcast upgrades the cablecard's firmware to 1.5.3_1101 at least.
I too am plagued by this problem, and reducing the tuners has not helped.
I have about 30 days left (BestBuy return period and an extended Tivo MBG) for Comcast to upgrade, or my Tivo days are over. ( Comcast says 'beginning of 2014' for upgrade in our area - Harford Cty, MD ) (I'm not holding my breath)
Long answer, it's a compatibility issue with the 6-tuner cablecard firmware and