ATI driver disables external monitor detection

[Harry Muscle]

I'm running Ubuntu 8.04 on a Dell Vostro 1000. I have an external monitor connected and it's detected according to the settings listed in System -> Preferences -> Screen Resolutions. The problem is that as soon as I install the driver for my ATI video using the System -> Administration -> Hardware Drivers it disables the detection of the external monitor. It's no longer listed in the "Screen Resolutions" window and it get's a messed up resolution put out to it. Weirdly enough if I install the ATI Control Center I can once again detect the external monitor inside the actual ATI Control Center but not inside the "Screen Resolutions" ... the problem is though that the settings in "Screen Resolutions" take precidence over the settings the ATI Control Center after I reboot.

Any help or input is highly appreciated,
Thanks,
Harry