Eclipse: An error occurred while collecting items to be installed

I have tried to update my Eclipse 3.5 Galileo plugins, and all what I have seen was:

An error occurred while collecting items to be installed
No repository found containing: org.eclipse.net4j.jms.api/osgi.bundle/1.0.0.v200806180305

I could not find the solution for a couple of hours. Finally, BINGO!, reinstalling EclipseLink packages solved it.

Just go to Help -> Install New Software ->, choose Galile update site Galileo - http://download.eclipse.org/releases/galileo and search for all installed EclipseLink packages. (You must uncheck Hide items that are already installed also.) The installed packages have grey icon. Just check them, press Next, and then Finish. Restart the Eclipse and then try to update plugins again.