I too been having the same problem with you. If I change my HD aspect ration to any thing higher than 480p. Problem is with 720p and 1080i. I would get snowy picture for 10 secs and it would black out with no picture display at all. Dishnetwork is no good. They are F ing sucks. Specially with VIP 211. I tried all guys of HDMI cables (short and long with different brands). Dish tech came out twice and they are clueless. They don't know about this problem. I got billed for $29.99 for house call service which nothing was fixed. Yes, Dish do offer the most HD channels. But, always issue with HDMI and they do want to acknowledge that they are having problem with vip 211 and software which the rolled out like every two weeks. Nothing fixed the HDMI problem yet. Looks to me they are ignoring this problem. I am done with Dish. I'm having TimeWarner in my area to get me a new service. I will not be much happy the choice I have with Dish, but I am going to get better picture resolution to the highest my TV can pickup (1080i).
Good luck to you with Dish. Maybe you email and phone them their fix the problem this time. More voice with problem complains, hopefully they'll be waking up.