Radeon 9800 Pro & Apple Cinema Display

I have been running FS 2004 on an Apple 20-inch Cinema Display at 1680x1050x32 using an nVidia GeForce Ti4400 video card. I use a DVI to ADC adaptor to connect the card to the monitor. Flight Simulator looks just gorgeous with this setup. After reading all the glowing performance reviews, I decided to upgrade my video card to a Radeon 9800 Pro 128. Unfortunately, I have not been able to get FS 2004 to run on the Apple monitor with the Radeon card. Before returning the Radeon card, I thought I would post here and see if anyone has encountered this problem - and solved it, or whether anyone has any suggestions as to how I might get this setup to work.What happens is that when I launch FS 2004, I get the opening splashscreen for about 10 seconds and then it goes black - sometimes with a white title bar, sometimes without. There is an hourglass for about another 10 seconds and once it disappears the machine is locked up and a power switch reboot is required. If I use a VGA monitor, the program runs just fine, although visually quite disappointing. So I think I can assume that the problem solely involves the interaction between the Apple monitor and the Radeon card.I have tried a clean re-installation of FS 2004 and pre-setting the display resolution in the fs9.cfg file to the Apple's native resolution of 1680x1050x32. This did not eliminate the problem. I have also tried a variety of other pre-set resolutions in the cfg, but to no avail. I think the problem may involve the fact that the Apple monitor runs at 60 Hz and cannot be adjusted while FS 2004 may be a 75 Hz program. (This Hertz stuff is way beyond my level of competency and I only mention it because a tech friend threw this out as a possiblity. I don't claim to understand it at all.) What led to this conclusion is that with the Radeon card, I also do not get any BIOS screens which he said are usually at 75 Hz. (I have no problem seeing these BIOS screens with the nVidia card so go figure.) Finally, let me just say that I have not encountered this problem with any program except for FS 2004.If anyone has any thoughts about this situation, I would greatly appreciate hearing from you. Thanks.Macwino