This should be fixed in 1.4.1 and higher versions of Geomajas. I have probably the same problem on Ubuntu 8.10 tomcat5.5. But what is worse I can not sometimes reload the application from tomcat manager -> hard to develop.
The catalina.out reports this:
Oct 4, 2009 10:12:36 AM org.apache.catalina.loader.WebappClassLoader validateJarFile
INFO: validateJarFile(/var/lib/tomcat5.5/webapps/majas-tutorial/WEB-INF/lib/servlet-api-2.3.jar) - jar not loaded. See Servlet Spec 2.3, section 9.7.2. Offending class: javax/servlet/Servlet.class
Oct 4, 2009 10:12:37 AM org.apache.catalina.core.StandardContext start
SEVERE: Error listenerStart
Oct 4, 2009 10:12:37 AM org.apache.catalina.core.StandardContext start
SEVERE: Context [/majas-tutorial] startup failed due to previous errors
Using Geomajas 1.4.1 should have the servlet-api problem fixed.