PS3 1080p Gray Screen

I was using my PS3 with a computer monitor that I have using a "HDMI to DVI" it was working fine, but I had a different monitor that I wanted to try with it and when I was ready to hook it back up to the 1080p monitor it looked all gray with a mix of different colors, when I try 720p it works, but when I try 1080p it's just the gray screen. I'm not sure if maybe I messed up the settings by trying to hook it up to the 720p monitor or not? Any help would be appreciated, thanks!