My guide did not seem to be updating to keep 2 weeks worth of info. Once I refreshed it, a program I wanted to record a week from now finally showed up. Is there a setting for auto refresh?
If your guide data is not refreshing each night I would recommend looking at the timeframe allowed for scheduled tasks to run. I have speculated that the default 3 hour window may not be enough time on some systems for all of the tasks that are run during the scheduled tasks timeframe to complete. I changed my times to midnight to 8:00 am and have only seen issues with less than 12 days of guide data a few times.