5 Green Bars but no Picture... HUh?

I've got an Sony XL1A and for the last couple of days it's been acting really odd when it comes down to OTA HD. If I check digital signal strength, I get 5 green bars nearly across the board (I live in the middle of Washington DC on the top floor of an apartment building), but when I go to tune into those channels I get the "NO TV Signal" blue screen. I am using a Kworld as my digital tuner, I have a MYhd laying around (shipping snafu, that I never felt like correcting), but I'm reluctant to pull the unit since I ultimately have to destroy my entertainment center to get to the Sony.


Has anyone else seen or heard of anything like this? I refuse to watch my shows in standard, and I'm missing Iowa / Ohio State right now, this is killing me. Help!