No idea what the BugSplat service is trying to tell me! However, went through all the normal recommendations to avoid the opengl issue, disabled the instructor and the welcome screen as advised but no help. By chance, I looked at the wine configuration (crossover/tools/manage bottles/control panel/wine configuration/Launch selected item. Select the graphics tab and turn off "Allow the window manager to decorate the windows" and " Allow the window manager to control the windows". This fixed the problem (whatever it was) so hope this might help someone else. I did find a ticket (I think) asking for help on the issue but it was closed so could not respond there.
I recall the app is rated bronze but personally, I would up that to silver now that all the issues are overcome.