Only works in low resolution mode

My xbox will boot up and look terrible (static-y and streaky). As soon as I get to the home page, everything goes black. I'm able to boot up in low resolution mode and I can see everything fine, but 720p and 1080 don't work with it. Before, it was prone to static effects. You could even hear static and sometime the screen would go black for a second. It was if the xbox wasn't grounding itself or the hdmi connection was grounded or something. I dont' know though. Any thoughts?