If you receive exceptions after loading a new model:
Use
Validate within the Model Editor to verify your model.
Clear the cache from the application context menu.
Clear the cache in the Navigator View.
If you receive an error when opening the Model Editor, this might be caused by a codepage problem - the model might have been
saved with a codepage different from the one it was opened with.
Global Workbench Actions do not work in Eclipse 4.n. This is caused by a known issue with the Eclipse IDE (search the Web site of the Eclipse Foundation for Bug 411765).