Was getting weird error when trying to compile a project today:

The project was not built due to "Problems encountered while copying resources.". Fix the problem, then try refreshing this project and rebuilding it since it may be inconsistent.

After a quick Google it appears this has happened to others and a re-install fixed the problem. I managed to fix the problem by:

Highlighting the project in the Enterprise Portal perspective then doing a File => Refresh from the menu.