I installed ACR 4.5 on my MacPro running OS 10.4.11 and all seemed fine except that if I open an image and try some settings with either a RAW or JPG file and then click on "CLOSE" the computer or CS3 the computer flashes bright for just an instant. as though I had triggered on of expose's hot corners. I have never seen this before. Obviously something is going on that the machine or CS3 does not like... and it never happened with ACR 4.4.1. Is there some place I can report this to the Adobe Beta folks for testing?