LED Cinema Display - Black Screen Problem!

Hi,
I have a Macbook Pro 17" (early 2011 with thunderbolt). I bought a second hand 24" LED Cinema Display and it has no guarantee. I started to use it. But I have a problem with the display. Sometimes display goes black for a second and comes back immediately. This happens a lot. I don't know what to do. I found a link (http://support.apple.com/kb/TS4045?viewlocale=en_US&locale=en_US) but I'm not sure to install it. I'm totaly desperate now. So If someone knew a solution for this problem or installed this firmware, please help me. I'm waiting your answers as soon as possible, thanks...

Go ahead and install the firmware update to see if it solves the problem. If it doesn't, you might want to check the Cinema Display cable by wiggling it around a bit. Perhaps it might be loose or intermittent.