when I turn TV off it turns my PC monitor off

Hello
I have a Samsung LCD tv (model here) plugged to an AV amplifier Onkyo TR-SX608 with an HDMI cable.
The Onkyo receiver is plugged to my GPU, an ATI radeon HD 5870 also with an HDMI cable.
The GPU is also plugged with a DVI cable to my PC monitor, a iiyama PLE2607WS

When I put either the amplifier either the TV in sleep mode or if I turn one of them off, it turns off my PC monitor.

It acts as if the HDMI port of the GPU said go**** there is nothing plugged here and cut the DVI output.
I dont know what to do, I looked at bios sleep mode potions, browsed ATI forums to check power saving options of the GPU, checked the TV forums and heard about CEC potential issues between the TV and the PC monitor, but franckly I'm at a total loss to at least circumvent a little the problem.
any idea what direction to look at ?
thanks in advance

Which is listed as primary? That shouldn't be an issue, but try it. Make your monitor your primary with the HDMI out as a seconday. On my system, I have 2 monitors on my GTX460 and my 42" plasma on a GT240N. I have them set to side by side by side. If I turn off the plasma, the two monitors blink for a sec while changing from 3 wide to 2 wide, but they come right back.

interesting

my pc monitor is listed as primary and the problem occurs

now reading your reply I tested and put the TV as primary :
with that setting I could switch the TV off, the PC monitor blinks a little then goes back to normal, exactly what I need except it put my icons / start menu etc on my TV, I imagine with some dual monitor softwares I could deal with it but it's not entirely satisfying.

thing is in catalyst control center (and even in windows display management) the HDMI is listed a number 1 monitor and the DVI as number 2, and you can either list number 1 or number 2 as primary.
what would be cool I imagine is to force the HDMI output to be listed as number 2.

ok I fixed the problem by changnig from No to Yes the BIOS option : Repost Video on S3 resume
I'm happy