IPolygon not defined, as an example

Hi,

I have done an AddIn in ArcObjects and Visual Studio Express 2008 (and 2005, prior) and now have ArcMap 10.1 and Visual Studio Express 2010 (all in Windows XP) and am trying to migrate my projects to the new versions. My problem is that most of the objects that I used are now undefined. If I go to the object browser, it can't find IPolygon, ILayer (or ILayer2) for 102 errors and 21 warnings. In my references, a lot of the dlls are not resolved per the Properties.

In the References tab for the project, it sees ESRI.ArcGIS.ADF.Local, but version is 0.0.0.0 and for Path it says: "<The system cannot find the reference specified>".

Has anyone encountered and solved this?

Thanks,

Dale