If during setup you forget to enter a postal code, the empty code gets stuck in the particular profile, even after you later enter the code on TV Options as RoderickGI's screenshot shows. This is a bug that was fixed last night.
If this is your situation, you can still fix it (without having to wait for the fix to be released). Firstly, make sure postal code is entered. Secondly, select the tuner profile in question, and click Configure button. Click Next button to the end of the wizard. Now the newly entered postal code will be saved in the profile. Thirdly, run "Load program guide..." manually. Make sure all settings on the dialog window are correct, especially the "Automatically load program guide everyday in the background" checkbox. Also make sure you look in the list of loading modes. Uncheck anyone that does not make sense anymore, and check the one(s) that has the mode with correct postal code.