Eclipse Problems View doesn't show Errors

For anyone else who is having this problem, I have found the answer:

Make sure that Eclipse recognizes your project as a Java project. Specifically, under Project Properties ensure that you have a Java Builder that is checked.

That way, your project will be built and you will see errors in the Problems view.

I want to post my story here if Google brings you to this question.

Somehow, "Project->Build Automatically" got turned off.

Turning it back on produces correct errors list.

I've tested that this is the case as far as Ganymede ( at the point of writing this post I am running Indigo )

This was my problem: http://solveme.wordpress.com/2009/01/06/eclipse-project-missing-default-java-builder/