I've run into a problem where some accounts cannot be deleted, while some others can.

This is what I get in mailbox.log when trying to delete one of these problematic accounts:

Code:
2009-02-05 18:35:46,908 INFO  [btpool0-0] [name=admin@etc;mid=1;ip=172.22.100.111;ua=ZimbraWebClient - FF3.0 (Win);] SoapEngine - handler exceptio
n
com.zimbra.common.service.ServiceException: system failure: unable to purge account: 8fc86b0e-f71a-4c8e-a7e0-8699099e1976
ExceptionId:btpool0-0:1233851746908:6355140ecc09636b
Code:service.FAILURE
        at com.zimbra.common.service.ServiceException.FAILURE(ServiceException.java:253)
        at com.zimbra.cs.account.ldap.LdapProvisioning.deleteAccount(LdapProvisioning.java:1925)
        at com.zimbra.cs.service.admin.DeleteAccount.handle(DeleteAccount.java:86)
        at com.zimbra.soap.SoapEngine.dispatchRequest(SoapEngine.java:433)
        at com.zimbra.soap.SoapEngine.dispatch(SoapEngine.java:288)
        at com.zimbra.soap.SoapEngine.dispatch(SoapEngine.java:167)
        at com.zimbra.soap.SoapServlet.doPost(SoapServlet.java:269)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
        at com.zimbra.cs.servlet.ZimbraServlet.service(ZimbraServlet.java:189)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:820)
        at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:487)
        at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1093)
        at org.mortbay.servlet.UserAgentFilter.doFilter(UserAgentFilter.java:81)
        at org.mortbay.servlet.GzipFilter.doFilter(GzipFilter.java:132)
        at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1084)
        at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:360)
        at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
        at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:181)
        at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:716)
        at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.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(HandlerWrapper.java:139)
        at org.mortbay.jetty.handler.rewrite.RewriteHandler.handle(RewriteHandler.java:350)
        at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:139)
        at org.mortbay.jetty.Server.handle(Server.java:313)
        at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:506)
        at org.mortbay.jetty.HttpConnection$RequestHandler.content(HttpConnection.java:844)
        at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:644)
        at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:211)
        at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:381)
        at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:396)
        at org.mortbay.thread.BoundedThreadPool$PoolThread.run(BoundedThreadPool.java:442)
Caused by: javax.naming.NamingException: [LDAP: error code 80 - DN index delete failed]; remaining name 'uid=usersdnhere
'
        at com.sun.jndi.ldap.LdapCtx.mapErrorCode(LdapCtx.java:3029)
        at com.sun.jndi.ldap.LdapCtx.processReturnCode(LdapCtx.java:2931)
        at com.sun.jndi.ldap.LdapCtx.processReturnCode(LdapCtx.java:2737)
        at com.sun.jndi.ldap.LdapCtx.c_unbind(LdapCtx.java:596)
        at com.sun.jndi.toolkit.ctx.ComponentContext.p_unbind(ComponentContext.java:634)
        at com.sun.jndi.toolkit.ctx.PartialCompositeContext.unbind(PartialCompositeContext.java:227)
        at javax.naming.InitialContext.unbind(InitialContext.java:379)
        at com.zimbra.cs.account.ldap.ZimbraLdapContext.unbindEntry(ZimbraLdapContext.java:610)
        at com.zimbra.cs.account.ldap.LdapProvisioning.deleteAccount(LdapProvisioning.java:1922)
        ... 31 more
I have checked db_stat and it shows no problems in LDAP.

I'm running 5.0.11_GA_2695.RHEL5-20081117051306.