I have been using v_1.1.0 on a Mac successfully for a while. Using it today it crashed unexpectedly, and then when restarted it comes up apparently as normal, but has lost the ability to draw anything in the molecule display area - menus and surrounds look fine. It doesn't matter whether I read in a molecule or try to build one - nothing appears, but clicking properties shows that atoms are stored. Most bizarrely, when I deleted the current copy, downloaded it agan and reinstalled it, the new copy had the saem problem, which makes me think that there is a 'session' file squirreled away somewhere outside the main package in Applications, that is remembering whatever setting has become broken and feeding that to the newly installed copy.
Interestingly, a freshly downloaded copy of v_1.0.3 worked fine.
Help would be greatly appreciated ...