Recently, my Tomcat 6 Development system decided not to start up anymore, but to throw this ugly exception instead:

03.10.2007 14:29:12 org.apache.tomcat.util.modeler.Registry registerComponent
SCHWERWIEGEND: Error registering Catalina:j2eeType=WebModule,name=//localhost/MACHacmsg,J2EEApplication=none,J2EEServer=none access denied ( register)
  at java.lang.SecurityManager.checkPermission(

No idea why, but i fixed it by adding the following line in the “grant” section of JRE’s lib/security/java.policy file:

permission "register";