I have had 509 on all day with NO problems. As most of you surely know, the CSR's at DirecTV have a motto: "When in doubt, first apologize profusely for the problem, then either blame it on the customer's receiver OR inform them they need a new access card." Oh...and as to the latter, they won't tell you they're charging you $20 for the new card until you happen to notice it on your next bill.
Here's what I've discovered that has helped correct the problem when you lose your HD channels from DirecTV...aside from re-setting your receiver by pulling the plug out for at least 20 seconds.
First, when you get a CSR ask them to put you through IMMEDIATELY to tech support. When they begin to ask questions just hang up and get another CSR until they do as they've been instructed when you THE CUSTOMER, ask for tech support, i.e.; put you through to tech support.
Assuming a "resend" of the DirecTV signal still has failed to get you "turned on" again...tell them to DEACTIVATE your access card...wait a minute...then RE-ACTIVATE IT again.
It's worked for me every time...at least 4 or 5 now to be sure.