Photoshop CS2 Defects

Dear friends!Accidentally I found one critical defect of Photoshop CS2 (v9.0, without update to 9.0.1):after converting a gray-scale image several times to RGB (or Lab) and then back, to grayscale, you get a considerable damage of your picture, which looks like a posterization. No defect of such a sort have been found in CS (v8.0).Therefore this feature of Photoshop immediately threw it back to the level of the middle of 90th years...There are some other errors in CS2 (in Actions, for example) but they are non-critical.Your Shu.