Have you tested your PS3 using the component cables? I ask because i had a similar problem and tested that and found that it worked fine. I was actually lucky enough to have two HDMI ports on my TV and eventually found that it was the port i had it on that was actually at fault. If you have access to another HDMI cord or port attempt changing them, However i have seen a few of the HDMI ports on things just stop working.
good luck