The Page Up and Page Down, DO NOT work as expected in the Channel List or the TV Guide. When you do a Page Up or Page Down, it actually shifts the cursor more then a page up or down. The amount shifted is determined by the Font Size that is set under the User Interface Options.
After a bunch of testing, if the font is set to 80, it works as expected. If the font is set higher then 80 then the page up or down will move more then one page..