We have seen this problem a couple of times.
Try this:
In YOUR solution:
1. Close all document windows.
2. Save All
3. Close and re-open Visual Studio
4. In a UI project (i.e., one that references System.Windows.Forms), create a new UserControl.
5. Edit the new user control in the designer
6. From the toolbox, drag a new ControlBindingManager to the form
7. Open the ControlBindingManager
8. Select the preferred control suite to be DevEx 7.3
9. Save and close the solution
10. Re-open the solution and try editing one of your views.
11. Delete the temporary user control created in step 4.