This is a known bug to the ViP's (known on this forum, but I don't know if Dish admits to its existence), and on this forum it seems to be more of the 722K's than others, but they to have the same problem; I've had it on both my 722 and 722K.
It usually happens only very rarely. Over 3 years, I think it has only occurred to about 5 or 6 recordings. In my case it just happens a time or two, then goes away, and is NOT even close to the trouble of having to RMA it.
For others, it happens more often and becomes frustrating. There really is nothing you can do about it as I have never seen a solution posted other than to RMA it if it happens a lot.
I know exactly what it's like and I feel your pain. Do a search and see how far back this problem goes, and just when you think Dish may have fixed it, someone like you posts the same bug. Few things hurt more than sitting down to watch that movie are favorite episode of a TV show and BANG! It all ends in 1 minute.
This bug seems to occur in bunches: 2 or 3 recordings for like a day or two, then perfectly fine for several months, then it happens again, then maybe OK for almost a year, then . . . . I don't know if even a complete dump and reformat works--which I DO NOT recommend for you at this point. But I would love to know if any of the more than a few who have had this happen to them came across a real solution.