Thank you all for your replies. Let's hope Apple will fix this issue. Strange that it isn't the same problem for everybody. I also did a clean install, but this was the result. Photo mechanic isn't the only program which gives me problems. Unfortunately, the problems I got with my Adobe CS5 are way bigger, and they just don't support it anymore. But I got the feeling that also with Adobe, not everybody is experiencing these problems, so it might be either a hardware issue, or something that is more or less apple ID related. Can it also be that the issue can also be caused by other installed programs, even when they are not running? Some kind of conflict?