Program guide not updating

The program guide on my HR20-700 is only showing for a few hours in advance. After that some shows are there, but many say 'Upcoming: Title not available'. My wife bumped the power today and the unit reset (I since bought a ups and its charging before plugging the dvr's in) but should that cause this problem or do I have something else going on? I haven't had this happen before when losing power due to a storm or whatever. My todo list still shows programs in advance and when I do a search everything seems to be ok. The guide is just missing almost everything. Any ideas anyone?

Edited to add that I do have a Seagate 750gig external drive connected through eSata.

Thanks.