PS CS3 (mac) vanishing setup icon??? Help?

[kirstenmary]

I am trying to install Photoshop CS3 upgrade (from PS7) on my Mac G5, and I can't even get the install to run. I click on the icon, it flashes in the dock, and then it disappears.

Can anyone help me? I have all of the system requirements, and I have never had the beta version. I do, though, have Elements in addition to 7. Could this be the issue?

Thanks!