Those errors indicate a signal issue to the TV outlet. It can be inside or outside issues with damaged drop cable, loose / wet / corroded fittings, excessive splitting or upstream into Comcast's RF portion of the plant.
If you can check for loose F connectors at the back of the box, the TV outlet and any accessable splitters, and check conditon of the coax jumpers. Make sure you are not routing your caox through any AC surge protector strip coax ports.
If nothing is loose, then contact Comcast support and insist on a tech visit to check the signals at the ground block, splitters and each TV outlet, and he can find and fix the issue.