Dual screen problem with HD4850

Hello,
I have a problem with my asus hd4850 when I add a second monitor to my VGA card and I overclock slightly my card (1Mhz additional needed).
During a reboot, I have a green screen on my main screen, the other when it remains off!
Thank you in advance for your help!!

Hi,
Perhaps the Graphics card does not like overclocking on 2 screens. Or it mismanages the 2 screens and resolutions ?

Hi
Do you have the same frequency control on the two monitors? to set the same resolution and frequency ?

The monitors are 2 different technologies. My main screen is a 19 "LCD (1208x1024 60Hz) and the second is a CRT 17" (1280 x 1024 75Hz). But ok, I'll try to save the CRT at 60Hz and retest.
What is strange is that if I overclock it would not be small as 1 MHz on the GPU or memory.
Without overclock, it works niquel.