Eclipse hangs on startup with the error essage " The org.eclipse.m2e.logback.configuration bundle was activated before the state location was initialized."

My eclipse version is Version: Luna Service Release 1 (4.4.1) The way I addressed that problem is: Delete the *.snap files under your eclipse workspace ".metadata/.plugins/org.eclipse.core.resources/" Be aware that after I restart eclipse, the projects under that workspace that I'm working on are gone. I need to re-import the projects later.