I have been through this project from top to bottom. Looked through VS and Microfour. The problem will go away then come right back somtimes after a cleaning or if I dump the datafiles in my bin\debug folder. Question, when I click the populate datasource settings button in a combobox, where is it looking for the business objects? This only happens with the combobox?

Hair on fire!

We actually rely on the DTE to give us the references.  We search through the projects within the solution.  Then for each project, we query the references and search for classes that are a subclass (at some heirarchal point) of BusinessLayer.  I am willing to bet that you have a reference issue somewhere.  That would be my first inclinication.

I know how you feel in regards to this though...sometimes .NET can hang onto things and it may end up being a simple fix in the end, but there are not any messages to clue you in!