I've had the same problems a couple of times. Restarting Eclipse normally helps
I have restarted it several times and also recreated my project in eclipse. Somehow the debug configuration window seems disabled. I tried doing it through using this URL
Configuring and Launching a Server is the step I am unable to get working.
Also I am unable to see the standard war file I create through the 'Packing configurations' in my eclipse project. I have created the war and it is visible through the windows explorer but eclipse is not picking it up on 'Refresh'