I don't have DirecTV. As a result, the term "99°W" means nothing to me, but I'm passing this along in case it's still not fixed at the time of posting: It's not affecting all HD channels, just channels broadcast from their satellite at 99ºW. DirecTV acknowledged it's a satellite issue that they're working to fix ASAP. In the meantime, tell folks that they can set the Display Options to "Show All Channels" to see the SD channels and view the standard definition version instead of the HD channel.
That was pretty bad. A lot of the HD channels are on their 99 degrees west satellite, including ESPN, NBCSN, and FS1. Everything was back to normal after about 5 or 6 hours. Some people are saying that it was interference caused by a solar storm, but I am not sure how that would just cause problems with the 99 satellite. Also, signal strength remained normal throughout. My guess is some software issue with DirecTV's data stream. They just updated their receiver software a few days ago.
I had wondered what was going on. I woke up from a nap and turned on the tv only to see that some of my most watched channels were going haywire. Lucky enough for me I was heading out anyway, to a birthday gathering.