Cinema display brightness and black out issue

Hello guys and gals,

I use a 2011 17" mbp hooked up to a 27" cinema display primarily as a window 7 machine. After recently logging on using Snow Leopard I saw an array of software & firmware updates which had built up over the past 6 months (roughly) so I installed them all. Immediately after doing so I started getting problems with random ACD black outs and issues with brightness (ACD seems very dim despite being set on highest brightness).

As such a decided to upgrade to Lion as I read somewhere that some of the the firmware updates apple recommended I install were only compatible with Lion and not Snow Leopard. The problem still exists after installing Lion.

This problem occurs on both operating systems and can sometimes (only sometimes) be fixed by switching the display off and on at the mains. It will then reoccur at some random point in the future.

Anybody aware of similar issues and/or a fix?

Thanks