Cinema Screen Blackout - a Thunderbolt problem??.

As apparently MANY others we also have a problem with our 20 inch Cinema Screen. We have used it for several years with NO problems, that is until we got our 27 inch iMac with Thunderbolt. Almost immediately it started blacking out. Finally took the screen to an Apple store, they hooked it up to one of their computers and said "it is working fine". While talking (still on their computer) after about ten minutes it went black!!. So it was obvious it was not OK!. As we had bought it some years prior, I was told they do not repair items over a certain age and "sorry but cannot help". Not only that but I had to buy a Thunderbolt connector to be able to use it as a side screen for the new iMac, which also cost over $30 - there has been speculation that the problem could be something to do with Thundebolt!.

As stated by others, it's an expensive item and one would hope for that amount of money it would last for many years and/or we could get some help regarding repairing the item.