If I visit a an email tool then view the permissions helper. When I click back the index for the email archive is displayed again, but none of the links work. I think that the log lines related to this are:
@4000000049c21cdf18b182a4 WARN: Exception helper class not found java.lang.ClassNotFoundException: org.sakaiproject.authz.tool.PermissionsAction (2009-03-19 10:22:13,414 TP-Processor2_org.sakaiproject.cheftool.VelocityPortletPaneledAction)
One problem with this bug is that there is no obvious UI part that shows there is something wrong.
I know using the back button is not advised, but this really confuses users.