[m2e-users] class not found when launching project from Eclipse

[Ted Yu <yuzhihong@xxxxxxxxx>]

Hi,
I am facing a strange problem.
In Eclipse workspace I have multiple projects.
Within project main, I can navigate to org.apache.log4j.Logger by pressing Shift+Command+R - log4j jar is among Referenced Libraries

When I run/debug this project, I see:
Caused by: java.lang.ClassNotFoundException: org.apache.log4j.Logger
    at java.net.URLClassLoader$1.run(URLClassLoader.java:200)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:315)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:330)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:250)
    at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:398)

This is my OS:
Darwin tyumac.local 10.3.0 Darwin Kernel Version 10.3.0: Fri Feb 26 11:58:09 PST 2010; root:xnu-1504.3.12~1/RELEASE_I386 i386 i386

I am using Eclipse Java EE IDE:
Build id: 20090920-1017

Can someone provide some hint ?

Thanks