In one of my projects I am trying to set Data Source Settings on combo boxes.  On all of them I have tried it comes up and then the settings form disappears and I see the wait window saying it is looking for business objects.  This just stays up and I never get to the population data source settings.  I end up having to exit the project and can't get the settings to come up.  This is the only project I have seen it happen in, but it happens on all of the combo boxes.

Try this...create a new StrataFrame application project.  Add a single BO and then open the BO Mapper.  More than likely the error will not persist.  If this is the case, then we need to begin disecting your other solution and see if there is anything different that could be throwing the error.  For example, do you have solution folders or anything out of the norm?