The guide says 'no guide data' but clicking on a channel icon shows a guide for that channel

If you can see the channel logo icons, or channel names, in the guide but there are no programs listed then make sure that the date and time in Windows is set correctly. Having the date to set to the wrong year will cause the guide to appear blank.

Note: With the wrong year set in Windows the single channel guide view in media center will still list programs because the single channel view uses the date and time from that channel's TV signal.