Today the users began using the zimbra 5.0.16 deployment in earnest and mostly it is going well (besides moans of web client being "slow" compared to outlook).

Going though the logs at the end of the day, however, I have notice quite a few occurrences of the following WARN message:

2009-07-27 15:41:45,531 WARN [btpool0-294] [] log - /service/home/~/
com.zimbra.common.service.ServiceException: system failure: native formatter failure
ExceptionId:btpool0-294:1248705705529:a73f676bf1ed6516
Code:service.FAILURE
at com.zimbra.common.service.ServiceException.FAILURE (ServiceException.java:253)
at com.zimbra.cs.service.formatter.Formatter.updateCl ient(Formatter.java:275)
at com.zimbra.cs.service.formatter.Formatter.format(F ormatter.java:87)
at com.zimbra.cs.service.UserServlet.doAuthGet(UserSe rvlet.java:493)
at com.zimbra.cs.service.UserServlet.doGet(UserServle t.java:396)
at javax.servlet.http.HttpServlet.service(HttpServlet .java:707)
at com.zimbra.cs.servlet.ZimbraServlet.service(Zimbra Servlet.java:190)
at javax.servlet.http.HttpServlet.service(HttpServlet .java:820)
at org.mortbay.jetty.servlet.ServletHolder.handle(Ser vletHolder.java:487)
at org.mortbay.jetty.servlet.ServletHandler$CachedCha in.doFilter(ServletHandler.java:1093)
at org.mortbay.servlet.UserAgentFilter.doFilter(UserA gentFilter.java:81)
at org.mortbay.servlet.GzipFilter.doFilter(GzipFilter .java:132)
at org.mortbay.jetty.servlet.ServletHandler$CachedCha in.doFilter(ServletHandler.java:1084)
at org.mortbay.jetty.servlet.ServletHandler.handle(Se rvletHandler.java:360)
at org.mortbay.jetty.security.SecurityHandler.handle( SecurityHandler.java:216)
at org.mortbay.jetty.servlet.SessionHandler.handle(Se ssionHandler.java:181)
at org.mortbay.jetty.handler.ContextHandler.handle(Co ntextHandler.java:716)
at org.mortbay.jetty.webapp.WebAppContext.handle(WebA ppContext.java:406)
at org.mortbay.jetty.handler.ContextHandlerCollection .handle(ContextHandlerCollection.java:211)
at org.mortbay.jetty.handler.HandlerCollection.handle (HandlerCollection.java:114)
at org.mortbay.jetty.handler.HandlerWrapper.handle(Ha ndlerWrapper.java:139)
at org.mortbay.jetty.handler.rewrite.RewriteHandler.h andle(RewriteHandler.java:350)
at org.mortbay.jetty.handler.HandlerWrapper.handle(Ha ndlerWrapper.java:139)
at org.mortbay.jetty.Server.handle(Server.java:313)
at org.mortbay.jetty.HttpConnection.handleRequest(Htt pConnection.java:506)
at org.mortbay.jetty.HttpConnection$RequestHandler.he aderComplete(HttpConnection.java:830)
at org.mortbay.jetty.HttpParser.parseNext(HttpParser. java:514)
at org.mortbay.jetty.HttpParser.parseAvailable(HttpPa rser.java:211)
at org.mortbay.jetty.HttpConnection.handle(HttpConnec tion.java:381)
at org.mortbay.io.nio.SelectChannelEndPoint.run(Selec tChannelEndPoint.java:396)
at org.mortbay.thread.BoundedThreadPool$PoolThread.ru n(BoundedThreadPool.java:442)
Caused by: java.lang.ArrayIndexOutOfBound***ception: 2089
at com.zimbra.common.mime.MimeDetect$Magic$Rule.detec t(MimeDetect.java:154)
at com.zimbra.common.mime.MimeDetect.detect(MimeDetec t.java:301)
at com.zimbra.common.mime.MimeDetect.detect(MimeDetec t.java:355)
at com.zimbra.common.mime.MimeDetect.detect(MimeDetec t.java:347)
at com.zimbra.cs.service.formatter.NativeFormatter.ha ndleMessagePart(NativeFormatter.java:164)
at com.zimbra.cs.service.formatter.NativeFormatter.ha ndleContact(NativeFormatter.java:146)
at com.zimbra.cs.service.formatter.NativeFormatter.fo rmatCallback(NativeFormatter.java:95)
at com.zimbra.cs.service.formatter.Formatter.format(F ormatter.java:84)
... 28 more
The "caused by" line refers to an ArrayIndexOutOfBounds Exception: 2089 error and I can find nothing in the forums relating to it.

Any idea what might be causing this?

(the editor is censoring the caused by line)