I have a direvtv hr21. Yesterday I came home and all the hd channels say searching for satellite signal. the standard def channels and the original hd channels in the single digits work fine. My 3 other sd receivers in the house are all working fine. I did all of the resets and still nothing. Called directv and they are sending out a tech in a week to look at it.

What does everyone think? It was very windy 2 nights ago, and I wonder if it knocked the dish out of alignment, or is the box going bad? Thanks for your responses.

I don't have DTV HD, but do have standard DTV and free OTA HD. It could be several things.
a) Failed LNB on the HD section of your dish (assuming it's a stand-alone LNB that supplies the HD signals)
b) Loose or broken coax between the LNB & receiver (again assuming that one LNB feeds the HD channels)
c) Receiver problem

I'd check your signal strength on the receiver menu. You should be able to shift between satellite feeds and check the level to the LNBs on the various satellites. I've seen a bad LNB cause the type of problem you describe with Standard Definition Satellite Digital with a dual LNB dish. Swapped the coaxes at the LNB and isolated the problem to a defective LNB. I'm not sure how DTV sets up their HD feeds, but Dish Network supposedly uses a separate dish for the HD feed.