I had the same 0551 error code after having my 942 for less than one week. I believe the exact wording was "a serious problem with the hard drive." DISH sent out a new one pretty quickly. Couldn't figure out why the drive failed. Both soft and hard reboots were fruitless. The receiver had pretty good ventilation, but seemed to run very hot. We also wondered about its proximity to my center channel speaker [magnetism etc] but couldn't really determine the cause of the failure. I never used it for recording, but that function did work on initial setup. My new 942, which I've now had for 2 days, is much more noisy and for some reason I think the PQ was a little better on the first one.
E* did kindly offer to prorate my monthly charges because the receiver "doesn't work like its supposed to" even though the loss of the ability to view programming was never an issue.