OT: External Monitor on iMac for FCP Review

I have a Apple 23" HD Cinema monitor attached to my iMac. Am having a curious problem with it coming on. Sometimes it does, other times I need to shut down and restart numerous times or unplug the monitor and plug it back in before it becomes active. I have it calibrated to NTSC/television. I don't understand why the iMac sometimes turns it on and other times it doesn't. It worked just fine as my main monitor at my office for about year before it began having this problem.

I use the monitor for reviewing output from FCP for DVDs, etc., and playback on television sets of family and friends and in the office.

Have I missed some setting on the iMac? If not, can anyone direct me to where I can research this situation.

Thanks.

Regards, Cyrus
iMac 27" Intel i7 Quad-Core; 16GB RAM; 2TB HD
Final Cut Studio, FCP X, Photoshop CS5, After Effects, etc.

Problem solved (I hope). Received a new power adaptor (the little square white box the power cord and the monitor plug into). Apparently, these units can go bad. Purchased the replacement unit through We Love Macs
www.welovemacs.com
$180 including shipping and tax
Monitor now works fine and does not seem to have the problem of turning on or not.

If anyone else is having any problems with the Apple HD Cinema 23" monitor not coming on, this might be the cause. I was having the same problem in my office when I was using it as my main monitor, which is OK 'cuz I bought a 30" monitor for the office... joy! joy!

Regards, Cyrus
iMac 27" Intel i7 Quad-Core; 16GB RAM; 2TB HD
Final Cut Studio, FCP X, Photoshop CS5, After Effects, etc.