I have a similar issue. I have a laptop, desktop and mac. The Mac rarely gets used but every now and then I need to use Photoshop on it and while I understand I can sign out on one of the other 2 PC's, when I try to launch the app on the Mac (having signed out on the laptop) it says I need to sign out of BOTH my other installations.
If I am allowed to use 2 installations at any one time, why do I need to sign out of all other installations?
Thanks, and sorry for hijacking your thread richrawl! :-)