Hi John, It means trashing the old completely and then installing off of the original CD. (make sure to pull out any third party extensions first; they won't cause any problems and can be used again) Carrara is not the only program that this affects. There are some others that I use that make the same recommendation. OSX is very good at finding application parts too. If your'e paranoid like me, I tried being careful and duplicated the orginal Carrara folder to another hard drive during my first Carrara OSX upgrade in case something went wrong during the upgrade. Everything went well and new files worked great. However, when I launched old Carrara files with the updated Carrara, the program would "find" some of the original program parts, referenced by the file, that had bugs from the original Carrara Application on the other disk. Then my updated Carrara would function in a buggy fashion. Trashing the duplicated application on the other disk fixed the problem. You probably didn't need to know that but you never know... Mark