If you use the database schema compare tool in Visual Studio 2012 you may see the following error when trying to compare the database with the source:
Cannot access a disposed object. Object name: ‘ModelStore’
For me, this was arose after installing the June 2013 update 3 for Visual Studio 2012.
I resolved the error by running Clean Solution and rebooting my machine.
Hopefully this helps someone, as the error isn’t exactly helpful 🙂