However there would be a first time for everything. I always carry a spare shiny new HDMI cable but HDMI HDCP handshakes (see the web please) can cause this. So we always try another source when we've swapped TV and cables.
In the past we could sidestep HDCP handshake issues by connecting over Component but those days are gone.
Be sure to have power downed, removed power from ALL HDMI DEVICES when swapping in gear. The HDCP gremlins are alive and well.
Bob
Bought Samsung 60 in plasma 5350. It blacked out (picture and sound) every 1 to 2 minutes. Lasted one second and came right back on each time. Took back to Costco and got another. This one not nearly as bad, but has done it 2 or 3 times tonight in about a 3 hour span.
I have heard that this could be a HDMI cable issue. But why same cable not as bad with the second TV? Any possibility it has anything to do with Ferrite Cores?

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic