0006743: dual monitor but only one works

I use dual monitor in my X86-64 computer with centos6.4 installed. Few minutes later, the Hibernation works. I move my mouse randomly then it is awaked. but in this situation, only one monitor works while the other does not work, unless I reboot my compute again. Normally, when I boot my computer and enter the CentOS platform, both monitor works well. but once it enters into Hibernation, and it is awaked later, it happen like the upper description I made. Can you help me out? hardware issues or software issues?<br /> <br /> best regards