I'm also having this problem. Here is the log file output. It seems to repeat for each key stroke. Just to note, using latest version of zimbra desktop. Autocomplete originally did work, it seems to have stopped over the past weeks.
2011-11-10 12:11:25,559 DEBUG [btpool0-533] [mid=2;] offline - unable to access GAL mailbox for
noname@noname.com
2011-11-10 12:11:25,588 INFO [btpool0-533] [mid=2;] SoapEngine - handler exception
com.zimbra.common.service.ServiceException: system failure: Caught IOException opening index
ExceptionId:btpool0-533:1320945085588:91c1c914846f151e
Code:service.FAILURE
at com.zimbra.common.service.ServiceException.FAILURE (ServiceException.java:248)
at com.zimbra.cs.index.LuceneIndex.expandWildcardToke n(LuceneIndex.java:459)
at com.zimbra.cs.index.MailboxIndex.expandWildcardTok en(MailboxIndex.java:458)
at com.zimbra.cs.index.query.TextQuery.<init>(TextQue ry.java:113)
at com.zimbra.cs.index.query.TextQuery.<init>(TextQue ry.java:67)
at com.zimbra.cs.index.query.parser.QueryParser.creat eContactQuery(QueryParser.java:660)
at com.zimbra.cs.index.query.parser.QueryParser.creat eQuery(QueryParser.java:606)
at com.zimbra.cs.index.query.parser.QueryParser.toTer m(QueryParser.java:353)
at com.zimbra.cs.index.query.parser.QueryParser.toTex tClause(QueryParser.java:325)
at com.zimbra.cs.index.query.parser.QueryParser.toCla use(QueryParser.java:288)
at com.zimbra.cs.index.query.parser.QueryParser.toQue ry(QueryParser.java:265)
at com.zimbra.cs.index.query.parser.QueryParser.parse (QueryParser.java:235)
at com.zimbra.cs.index.ZimbraQuery.<init>(ZimbraQuery .java:439)
at com.zimbra.cs.index.MailboxIndex.search(MailboxInd ex.java:143)
at com.zimbra.cs.mailbox.IndexHelper.search(IndexHelp er.java:125)
at com.zimbra.cs.mailbox.Mailbox.search(Mailbox.java: 3719)
at com.zimbra.cs.mailbox.Mailbox.search(Mailbox.java: 3688)
at com.zimbra.cs.mailbox.Mailbox.search(Mailbox.java: 3673)
at com.zimbra.cs.mailbox.ContactAutoComplete.queryFol ders(ContactAutoComplete.java:578)
at com.zimbra.cs.mailbox.ContactAutoComplete.query(Co ntactAutoComplete.java:340)
at com.zimbra.cs.service.mail.AutoComplete.query(Auto Complete.java:87)
at com.zimbra.cs.service.mail.AutoComplete.query(Auto Complete.java:73)
at com.zimbra.cs.service.offline.OfflineAutoComplete. handle(OfflineAutoComplete.java:57)
at com.zimbra.soap.SoapEngine.dispatchRequest(SoapEng ine.java:412)
at com.zimbra.soap.SoapEngine.dispatch(SoapEngine.jav a:287)
at com.zimbra.soap.SoapEngine.dispatch(SoapEngine.jav a:158)
at com.zimbra.soap.SoapServlet.doWork(SoapServlet.jav a:294)
at com.zimbra.soap.SoapServlet.doPost(SoapServlet.jav a:215)
at javax.servlet.http.HttpServlet.service(HttpServlet .java:725)
at com.zimbra.cs.servlet.ZimbraServlet.service(Zimbra Servlet.java:208)
at javax.servlet.http.HttpServlet.service(HttpServlet .java:814)
at org.mortbay.jetty.servlet.ServletHolder.handle(Ser vletHolder.java:511)
at org.mortbay.jetty.servlet.ServletHandler.handle(Se rvletHandler.java:390)
at org.mortbay.jetty.security.SecurityHandler.handle( SecurityHandler.java:218)
at org.mortbay.jetty.servlet.SessionHandler.handle(Se ssionHandler.java:182)
at org.mortbay.jetty.handler.ContextHandler.handle(Co ntextHandler.java:765)
at org.mortbay.jetty.webapp.WebAppContext.handle(WebA ppContext.java:422)
at org.mortbay.jetty.handler.ContextHandlerCollection .handle(ContextHandlerCollection.java:230)
at org.mortbay.jetty.handler.HandlerCollection.handle (HandlerCollection.java:114)
at org.mortbay.jetty.handler.HandlerWrapper.handle(Ha ndlerWrapper.java:152)
at org.mortbay.jetty.handler.rewrite.RewriteHandler.h andle(RewriteHandler.java:230)
at org.mortbay.jetty.handler.HandlerWrapper.handle(Ha ndlerWrapper.java:152)
at org.mortbay.jetty.Server.handle(Server.java:326)
at org.mortbay.jetty.HttpConnection.handleRequest(Htt pConnection.java:543)
at org.mortbay.jetty.HttpConnection$RequestHandler.co ntent(HttpConnection.java:946)
at org.mortbay.jetty.HttpParser.parseNext(HttpParser. java:756)
at org.mortbay.jetty.HttpParser.parseAvailable(HttpPa rser.java:212)
at org.mortbay.jetty.HttpConnection.handle(HttpConnec tion.java:405)
at org.mortbay.io.nio.SelectChannelEndPoint.run(Selec tChannelEndPoint.java:410)
at org.mortbay.thread.BoundedThreadPool$PoolThread.ru n(BoundedThreadPool.java:451)
Caused by: java.io.FileNotFoundException: C:\Users\Laszlo\AppData\Local\Zimbra\Zimbra Desktop\index\0\2\index\0\_9q.prx (The system cannot find the file specified)
at java.io.RandomAccessFile.open(Native Method)
at java.io.RandomAccessFile.<init>(RandomAccessFile.j ava:212)
at org.apache.lucene.store.SimpleFSDirectory$SimpleFS IndexInput$Descriptor.<init>(SimpleFSDirectory.jav a:76)
at org.apache.lucene.store.SimpleFSDirectory$SimpleFS IndexInput.<init>(SimpleFSDirectory.java:97)
at org.apache.lucene.store.SimpleFSDirectory.openInpu t(SimpleFSDirectory.java:63)
at com.zimbra.cs.index.LuceneDirectory.openInput(Luce neDirectory.java:140)
at org.apache.lucene.index.SegmentReader$CoreReaders. <init>(SegmentReader.java:136)
at org.apache.lucene.index.SegmentReader.get(SegmentR eader.java:605)
at org.apache.lucene.index.SegmentReader.get(SegmentR eader.java:583)
at org.apache.lucene.index.DirectoryReader.<init>(Dir ectoryReader.java:109)
at org.apache.lucene.index.ReadOnlyDirectoryReader.<i nit>(ReadOnlyDirectoryReader.java:27)
at org.apache.lucene.index.DirectoryReader$1.doBody(D irectoryReader.java:79)
at org.apache.lucene.index.SegmentInfos$FindSegmentsF ile.run(SegmentInfos.java:677)
at org.apache.lucene.index.DirectoryReader.open(Direc toryReader.java:73)
at org.apache.lucene.index.IndexReader.open(IndexRead er.java:316)
at org.apache.lucene.index.IndexReader.open(IndexRead er.java:262)
at com.zimbra.cs.index.LuceneIndex.openIndexReader(Lu ceneIndex.java:696)
at com.zimbra.cs.index.LuceneIndex.getIndexReaderRef( LuceneIndex.java:785)
at com.zimbra.cs.index.LuceneIndex.getIndexSearcherRe f(LuceneIndex.java:527)
at com.zimbra.cs.index.LuceneIndex.expandWildcardToke n(LuceneIndex.java:423)
... 48 more
