Twice recently the gridlines when pulling up the Guide are not in place - a very aggravating thing, to say the least because it means I can't see what the lineup is of a desired specific channel. (It shows a static image of programs but it is not capable of being navigated.) I don't know what causes the problem (does anyone?) but it eventually clears up later in the day. Who else has experienced this? What is the probable cause? Is there a more expeditious fix rather than to wait it out when it happens? I'm on cable using a HD-TiVo. I do not use VOD nor premium channels - only Extended Basic via Charter Cable firm.