30” Cinema Display – Can’t use full resolution

A month ago, I bought a Mac Pro Desktop and 30” Cinema Display in the U.S. Then, I moved to England for an educational program, and I just plugged in my machine on the British outlets with some adapters. The computer works fine but the 30” screen has a reduced resolution to 1280 X 800. In the States, it had been working fine on 2560 x 1600. When I go to System Prefs, the max resolution option is 1280 x 800.

I tried the traditional approaches to solving the problem: “Detect Displays” and starting in safemode an then trying to change the option, but nothing worked. I’m stuck with 1280 x 800 (which is really bad on a 30").

The only thing different between before and after is obviously the power supply. Both the Mac Pro and cinema display have a notice on them to say that they work fine on up to 240 V. But there must be some issue with the adapters… Do I need to buy a different kind? Or is it something else?

If anyone has advice, I would greatly appreciate it because I do not have a phone service yet--only school provided internet-- so I cannot call apple directly.

Thank you…