Are you trying with the latest 11 hotfix and 10.6.8 on any machines that you are testing this with (e.g., not a mixed environment)?
Could it be any of the font or other Snow Leopard compatibility issues listed here:
http://www.archicadwiki.com/SnowLeopard
Do you get a crash report when you force-quit? If not, run Activity Monitor, select the 'not responding' archicad process and click the Sample Process button in the toolbar. Paste the first 20 or 30 lines of that here.
Karl
One of the forum moderators
AC 28 USA and earlier • macOS Sequoia 15.2, MacBook Pro M2 Max 12CPU/30GPU cores, 32GB