I had this problem on a 322 for several MONTHS, until one of the software updates "fixed" the problem (I figured one of the downloads would eventually "fix" the uncommon problem--that's Dish Network, sometimes). I should add that Dish did "hit" the 322 to reset all passwords, but it did NOT work. If you have patience, and other STB's, and you otherwise like the STB you have, wait it out. If you can't wait, then you will have to RMA the unit.
I had an abnormal function on my old 721 that was extremely rare among STB's. I didn't want to RMA the unit. I just KNEW that one of the updates would correct it. It took months, but finally, it was "fixed." Of course, I'm talking about oddities that may affect an extremely small percentage of users, not the known problems that are well documented on boards like these.
Best of luck.