OK, I've searched high and low on this one. Usually I can find answers to just about anything but this one is evading me. I have a Dual G5 2GHz running OS X 10.4.9 with the Apple OEM Radeon 9800xt video card. The Sony HDTV is connected via a 25' HDMI to DVI cable to my G5. I have no problem selecting 720p (1280x720) and it works nicely, but when I try to select 1080i (1920x1080 interlaced) I get an image that never syncs up properly... I can see its the right size but there is a vertical rolling shutter effect that blanks out approximately half the screen at a time. Other interlaced resolutions give similar results. Just to rule out a problem with either my TV and/or the HDMI to DVI cable I hooked it up to a Dell PC and 1080i worked beautifully. I've tried playing with custom resolutions using SwitchResX, using some examples found here and elsewhere with no improvement... the problem with SwitchResX is that every time I create or change a custom setting I have to reboot to use it... given the number of parameters and ranges available, this could become a life long pursuit! I'm beginning to think its a driver or hardware problem with the video card, but if anyone has experience with a similar combination or suggestions how to narrow this down I'd certainly be greatful!

Karl