when i go to open or download an atachment from webmail i recive a error from tomcat http 500 and in the file /opt/zimbra/zimbra.log the next

2006-03-23 18:59:26,608 ERROR [http-81-Processor95] [] StandardWrapper[/service:UserServlet] - Servlet.service() for servlet UserServlet threw exception
com.zimbra.cs.service.ServiceException: system failure: proxy error
at com.zimbra.cs.service.ServiceException.FAILURE(Ser viceException.java:131)
at com.zimbra.cs.service.UserServlet.doGet(UserServle t.java:229)
at javax.servlet.http.HttpServlet.service(HttpServlet .java:689)
at com.zimbra.cs.servlet.ZimbraServlet.service(Zimbra Servlet.java:154)
at javax.servlet.http.HttpServlet.service(HttpServlet .java:802)
at org.apache.catalina.core.ApplicationFilterChain.in ternalDoFilter(ApplicationFilterChain.java:252)
at org.apache.catalina.core.ApplicationFilterChain.do Filter(ApplicationFilterChain.java:173)
at org.apache.catalina.core.StandardWrapperValve.invo ke(StandardWrapperValve.java:214)
at org.apache.catalina.core.StandardContextValve.invo ke(StandardContextValve.java:178)
at org.apache.catalina.core.StandardHostValve.invoke( StandardHostValve.java:126)
at org.apache.catalina.valves.ErrorReportValve.invoke (ErrorReportValve.java:105)
at org.apache.catalina.core.StandardEngineValve.invok e(StandardEngineValve.java:107)
at org.apache.catalina.valves.AccessLogValve.invoke(A ccessLogValve.java:526)
at org.apache.catalina.connector.CoyoteAdapter.servic e(CoyoteAdapter.java:148)
at org.apache.coyote.http11.Http11Processor.process(H ttp11Processor.java:825)
at org.apache.coyote.http11.Http11Protocol$Http11Conn ectionHandler.processConnection(Http11Protocol.jav a:738)
at org.apache.tomcat.util.net.PoolTcpEndpoint.process Socket(PoolTcpEndpoint.java:526)
at org.apache.tomcat.util.net.LeaderFollowerWorkerThr ead.runIt(LeaderFollowerWorkerThread.java:80)
at org.apache.tomcat.util.threads.ThreadPool$ControlR unnable.run(ThreadPool.java:684)
at java.lang.Thread.run(Thread.java:595)
Caused by: javax.servlet.ServletException: mountpoint loop detected

i am running in a fresh install of suse 10.0 with my apache running and zimbra's http redirect to port 81

sorry my english is very poor.

TIA