Dual monitor in OSX

[viper55666]

I have a phillips 19¨ TFT it has always worked fine in both OSX and XP (through Bootcamp) but since i installed the new ATI catalyst control center in XP when i boot into OSX the second monitor does not work. When i go into displays the 'appearance' tab does not show therefore cannot adjust the second monitor settings, if i hit detect displays the second monitor switches on, displays a no signal message and switches off again. Any ideas??