ATI Radeon X1900 XT & Leopard bad mix

Question

I continue to have bad video problems and system freezes. As a movie editor this is killing my business. I have repeatedly asked for assistance from Apple and they have gone mum. Graphic lines prevade my screen, I can't take screen shots. Try and work in spaces on different projects results in a system freeze and loss of hours of work on end. Apple had to have known of these graphic problems with the X1900 yet they went right ahead and released Leopard, provided no caution to those of us who spent thousands of dollars on high end systems and 30" Apple displays.
NONE of these problems ever came up with Tiger. Not a one. Yet my business and income is going straight down the tubes because of Leopard. Does anyone have any advice on how I can get (1) assistance from Apple to resolve these graphical problems and/or (2) their own advice on tricks, tips or workarounds I may be able to use to at least get some work done?
I cannot take on new work and feel confident I can complete it.

Answer 1

I have tried all of the advice offered from cleaning the heat sink to installing the latest firmware and drivers. Apple Tech support has been ridiculous and this morning I had no alternative but to back peddle to Tiger. I have lost so much work, applications that will take months to find and reinstall, had to pay for updates that were now considered "new" installs and I remain furious with Apple.
For those who say "back up" I did make a backup on to the external drive of my previous system but was assured time and again by Apple Geniuses and tech support that the problems I was experiencing would dissipate and/or be corrected quickly. I had no alternative but to erase the backup if I was going to utilize Time Machine (because the external simply isn't THAT big). Believing Apple was my mistake and believing in Leopard was the bigger mistake.
At the moment my biggest concern is getting my iPhone to show up in iTunes. It isn't recognized at all and I have no idea how to change that. I'm at the latest release and plug it into the dock does nothing but recharge the battery. iPhoto won't open at all (it was suggested that iPhoto was denying iTunes to see it) and I don't know how to fix that unless I reinstall all over again. This has taken me hours and hours to get back to a working system.
I could not run the machine for more than an hour before it would simply freeze solid. I ran TechTool on every piece of hardware, ram and hard drives and they all passed with flying colors.
Is the problem Leopard? Definately. I can confirm that now because with Tiger my system is back to a solid foundation, my screen displays as it should. Sadly I had to learn a horrible lesson in believing in Apple's claims which I now take with a grain of salt. Months of work is gone or has to be pieced back together. I lost the majority of stuff from the main drive - pictures, graphics, music, movies, receipts for software residing in the documents folder. No matter how often I tried to back those folders/directories up it would never reach completion because the system would freeze.
"That can't the fault of Leopard..." - of course it is. Now back with Tiger I've had no system freezes. It isn't a hardware problem. I paid over $7,000 for this system and its additional software programs (FCP, Aperture, Logic, CS3, etc) and Apple trumpeted Leopard as "ready to go" when it is no where near ready for the professional user.
I won't do it again and I won't believe in Apple again. I am disgusted, angry and disgruntled.
John S. Hudson