I just got a Roku, and I can get it to work via component video cables, but not via HDMI. This is a problem for me. According to Roku support forums, though, it's a known issue that the Roku has a lot of HDMI handshake issues with certain TVs...so I was about to give up and just go with the component video cables.

Problem I'm having now is that after fiddling around with the cables in an attempt to get HDMI to work, the HDMI connection between my cable box and TV and between my DVD-player and TV no longer works. (I have a projector TV with no onboard audio, so I had HDMI connections to both my cable box and my DVD-player-home-theater-amplifier, and those HDMI connections used to work fine.) And now NONE of them work. I'm starting to think that maybe I somehow fried the HDMI port on my projector TV (I was, after all, pushing the HDMI cables in and out of there pretty hard as i was trying to get the roku set up, thinking maybe the cable just wasn't all the way in.)

In any case, is there any way to test the port itself to see if it's working? The 3 devices that ostensibly are HDMI compatible are now no longer working in the port, and that had really been the only way I was able to check if it was working. Now all I get when I switch to the HDMI input on my projector-TV is a "no signal" message on screen, suggesting that it doesn't think anything is connected to the HDMI port at all.

Its doubtful all those devices HDMI ports would fail at once. More likely scenario is a bad cable or perhaps a bad port in your display. Does your projector have more than one HDMI port? Also for future reference the "pushing it in harder" solution doesnt really work with digital connections. In the long run it leads to more harm than good.

I guess I wasn't clear. Yes, that's which port I'm talking about when I say I want to test one b/c, as you say, there's no way all those ports just happened to fail at once. I'm talking about testing the 1 and only HDMI input port on my projector TV's back panel.

Beyond just hooking up a source device and seeing if it works I'm not aware of another way to test an HDMI port.

Since you have tried hooking up 2 different source components via HDMI. I would say the odds are good that the HDMI port in your display is bad. Assuming you have ruled out a bad cable as the culprit.