Because of changes made to certain controls in the Operating System for Leopard, some of the dialogs in our program which use those controls cause the program to crash. We have reported the problem to Apple but so far they have not fixed it. Our latest CX 5.5 version of the program does have code changes which avoid the problem and will run under Leopard.
If you are running the CX 5 version of the program there is a free patch to version 5.1.1 which works around the problem. You must have updated your program to CX 5.1, also a free updater, before the running the patch. Both the 5.1 updater and the 5.1.1 patch can be downloaded from <http://www.strata.com/support_updates.asp>. Versions of the program earlier than CX 5 will not be fixed for Leopard.
If you do not want to Upgrade to CX 5.5 then you will have to avoid any dialog which allows you to open a file. You can open your model files by double-clicking on them or by dragging them to the Strata 3D program icon and dropping them. The only way to load images for new Textures is by copying them to the Clipboard in Photoshop then pasting them into the Texture dialog.