DIRECTV receivers, like all computers, have a tendency to get bogged down after a while. This is especially true of DVRs, which have a lot of things going on. With computers, many of these tasks are cleaned up when you restart, but you hardly ever restart a DVR. When you “power it off” you’re just turning off the video and audio. In order to restart, it takes a little more.
If you want to clean up a lot of the behind the scenes stuff on your DVR, press the red button to reboot it, then wait until you see live TV, then immediately reboot it again. This “twice within the same 30 minutes” procedure lets your DVR know that you’re serious, and it dumps all guide data and other temporary data and rebuilds it from scratch. It also runs basic hardware tests to make sure everything is working properly. Your settings and series links shouldn’t be affected unless there’s a serious hardware problem.
You may lose access to on demand programming and interactive features like ScoreGuide for a day or so after this happens and you probably won’t have any guide data past about the first 12 hours. This is perfectly normal. All that stuff will be rebuilt from scratch and it should help with at least some of the sluggishness that tends to set in with DIRECTV receivers over time.