I too would like to install Photo! Editor on a USB drive and use it on different computers.
I have loaded the program onto a portable drive on my Vista machine. It works fine there.
When I move the drive to my XP laptop, it comes up in Batch mode. (The Rotate functions are disabled.) I seem to be able to get out of Batch mode by clicking on File and selecting a single picture.
The problem I have is that none of the buttons do anything.
I am in Administrator on both machines.
Do you have any insight into this problem?