Thanks for updating your signature, Jack. I just assumed that since you switched to PC that you switched to a new PC with Windows 10... Do note that officially, ARCHICAD 21 is considered 'compatible but not tested' on Windows 7.
The last officially fully compatible Windows 7 version of ARCHICAD was version 19:
https://helpcenter.graphisoft.com/technotes/operating-systems/windows-7/
I've not seen any (?) discussion here of people having issues with Win 7 and AC 21 ... but just be aware that it is possible that you may run into something. Good luck with the transition.
Karl
AC 28 USA and earlier • macOS Sequoia 15.2, MacBook Pro M2 Max 12CPU/30GPU cores, 32GB
One of the forum moderators