Technical Guys, any ideas on this one?

Right, problem is as follows. Recently acquired a ps3, saw machine working fine on the guys tv through an hdmi cable. Brought it home hooked it up to my tv, all i get is sound and a picture full of multi coloured vertical lines for a moment before tv gives up and tells me there is no signal.  Thought maybe the ps3 was set to some weird output my tv didnt support so took whole lot to my mates, plugged in using same cables etc, works fine straight out of box, even played half n hour of ghosts. Did a system reset cos previous owner left all his account and games saves etc on it, still worked fine on my mates telly.Brought it home still no picture.... Now the kicker here is that my xbox 360, using the same hdmi cable into the same hdmi port works perfectly....

Having done all this it seems to rule out failure in any one of the components. ps3 works fine on my mates telly using the same cables, the hdmi port seems to work fine with a 360 in it so clearly the lead and port work, so what the hell is going on???

Also why doesnt the ps3 automatically know if you are using a hi-def set up or the bundled a/v lead cos i cant get a signal out of that either? i even used an adapter for a scart hook up but no joy there either( although this was an xbox adapter, i dont know if the pins are perhaps different?)

Any ideas?