Q: I am having trouble with a LaCie 526 monitor working with my new Mac Pro.  When I boot up, I see the sign-in screen for a second, then it disappears, reappears with some of the screen pixelated and the spinning beach ball -- and then freezes. Any thoughts

The LaCie is connected via DVI to thunderbolt adapter.  It had been working, and then when I switched off the computer and restarted several days later, I see the signon screen flash quickly, followed by nothing, followed by the signon screen and spinning beach ball and it simply freezes.  Any thoughts?