I started getting this error every day from 4-5pm for a week. I still have my original DTV tivo sir4040 and it was just fine during the 771a on the new system. I have an HR24 -200 with one other standard receiver and the whole home system. I have my receiver using a wired connection to my home router and the whole home uses a little box with the coax cable wiring. I spent a bunch of money getting direct tv out to fix the problem, signed up for the protection plan and all that. Didn't have any issues for about a year with the system prior to this. They were actually here during the outage, ended up replacing the little power injector uint that is between the dish and dvr and the lnb's on the dish. Dish alignment was fine, nothing else could be found, everything worked again. As soon as they left I walked in and 771a on the tv. It seemed to clear up and work from then on out for a couple months.
Well today about 1 771a is on my tv again. I turned everything off, still 771a. Reset the power injector thing as well. Tivo works just fine. I started thinking I wonder if it would have anything to due with my internet? My internet was up and running just fine but it was the only thing that is different between the tivo and the new dvr. Just for fun I powered off my router and cable modem, turned off the tv and dvr, didn't unplug, just turned them off with the remote, unplugged the little dish power injector and waited about 2 minutes till the light went out on it. I then booted up my router, cable modem and went back over, plugged in the dish power injector unit, waited about a minute till I thought the internet was back up and turned on the tv and dvr, there was tv again.
So if you are getting this error this could be something you can try, hope it works for you.