My assistant cringes whenever he hears the word "known issue." In this case, it was Adobe CS4.
Our Macintosh labs contain Intel iMacs. When the conversion came from PPC to Intel, we bought a test group of the original released version. We refer to this group at work as the "white iMacs." Later, when we purchased Intel Macs for the rest of the labs they had already moved on to the more familiar black and silver versions. Enter CS4. Adobe released the product, and I was given the assignment to remove CS3 on the lab computers and replace it with CS4. That, in itself, is a long rant against my constant struggle with the Adobe installer. In short, it got done. However CS4 had a major problem in the lab where the white iMacs were deployed. In Photoshop, certain tools like the crop or the pen would disappear when used. The screen around the window would also make green/pink/red noise areas which would change or get worse when the window was modified.
My first hunch was correct, that the video card couldn’t redraw the screen. How I dealt with this was analyzing RAM usage, and reinstalling the system software from our college image. This didn’t work, which led me to a panic thinking that our software image (which is a generic Leopard software build developed with specific college tools installed) didn’t contain the correct video drivers for the white iMacs. They have an NVIDIA GeForce 7600 GT, while our modern black/silvers are an ATI Radeon HD2600. Software update should have taken care of the driver issue, but my internal devil’s advocate left often the suspicion that this may need to be tackled directly.
After lunch (and a fresher perspective as a result of nutrients entering my system,) I hit the Adobe knowledgebase and found the issue. It was indeed a screen redraw problem, and I was further correct in that it specifically involved the videocard. Here is why: CS4 uses the GPU of the videocard itself for screen redraw instead of the machine’s CPU. The NVIDIA card could not handle this change. Owners of white iMacs or machines with non-compatible graphics cards beware.
Details and troubleshooting here: http://kb2.adobe.com/cps/404/kb404898.html