definately follow the advice of the other guy.... I was having a similar problem and without contacting comcast (yet again) I was able to determine that I did in fact have a signal problem, now I can contact comcast with more info than just "my guide isn't working.... if you wanna check this yourself, it's pretty easy.... you can use remote or buttons on cable box..... turn off cable box and quickly press ok/select button (you have 2 seconds) this will bring up a crazy looking screen (kinda reminds you of an old computer boot screen) this is a diagnostics screen... now using your arrow buttons go down to the third one, it should say OOB status... The SNR and AGC need to both show GOOD. If they don't then there is a signal issue that needs addressing. now to exit this screen simply hit power, then hit power again to turn on cable box.... good luck with your issue, mine turned out to be the coax coming to the house from the utility pole, it was pretty old and was worn through in a spot that rubbed a tree branch over the years!!!!