I recently upgraded to a new iMac running OS 10.6.2 and the Adobe Master Collection. I have yet to extensively try all applications. In Photoshop CS5, 12.0.4, I have an issue where the screen does not update the latest action. For example, If I start with a white backgrouns, and select the pencil tool, and draw a red line, it may not display, until I draw a second line, and then, only the first line will appear. In other words, the display is one move behind me. This is sporadic. Sometimes, the display is fine, and current. Other times, it will remain one move behind me throughout. This is also true of Levels adjustments, and most other tasks I perform. I usually have to do a task, then change to the lasso tool, as it is non-destructive, and tap the image to make the previous task appear, and then return to my work. This is new with CS5; I had not encountered this with any previous version. I have also encountered a couple of serious corrupt file problems, end-of-file errors, that I have not encountered before, where completed files have been trashed.