I don't believe it is a firmware problem. I think someone else would have mentioned it if it was. But feel free to try.
I'd also like you to connect to a different display, which seems most likely to me.
Well just for the case, there is nothing to laugh at.
It is definitively the firmware! as the firmware of Jan 1st 2013 did not work i went back straight to Nov 26, 2012, whereas my tv headend is showing the CORRECT COLOURS.
Its the firmware, its the firmware!!!!!
so the change must have been between Nov26 and Jan 1st,. actually did not check any update between these dates, because life is calling me, im tired as hell. ill check the lineup to find out which update exactly causes the mess.
it must be end of december because i remember my openelec did the same colourscrewing as my wheezy installation now. after some reboot there were wrong colours using composite and nothing i could do about it, so i went to xbian, which works until now. (but as long not so good as openelec did, but thats for another thread.
pls keep investigating the thing. There WILL be more in the future, but there seem not to be so much people using both dvi monitor and tv headend at the same pi. or they dont care about pluging out the hdmi cable. im sure there will be more.
unfortunately the reason for me to switch to tv headend, an xbmc installation does not work with the firmware of november, so there isnt anything to be happy about.
ill report which firmware update causes the change. tomorrow.