Brand new desktop install on windows 7 64 bit. Zimbra server is foss v8. This is the error report from the zdesktop client:
Product name: Zimbra Desktop
Product version: 7.2.2
Build ID: 11951
Release type: GA
OS Platform: Windows 7 x86 6.1
Time of event: 2013-10-19 14:29:04
Error type: service.FAILURE
Item ID: 1712
Error summary: message sync failed

Failure details - PLEASE REMOVE ANY SENSITIVE INFORMATION
----------------------------------------------------------------------------

com.zimbra.common.service.ServiceException: system failure: Unable to read/write message id=1712
ExceptionId:btpool0-62:1382207344670:19752476a8e72cdc
Code:service.FAILURE
at com.zimbra.common.service.ServiceException.FAILURE (ServiceException.java:253)
at com.zimbra.cs.mailbox.InitialSync.saveMessage(Init ialSync.java:1306)
at com.zimbra.cs.mailbox.InitialSync.syncMessagesAsTg z(InitialSync.java:1133)
at com.zimbra.cs.mailbox.InitialSync.syncMessages(Ini tialSync.java:1047)
at com.zimbra.cs.mailbox.InitialSync.syncMessagelikeI tems(InitialSync.java:423)
at com.zimbra.cs.mailbox.DeltaSync.syncItems(DeltaSyn c.java:239)
at com.zimbra.cs.mailbox.DeltaSync.deltaSync(DeltaSyn c.java:185)
at com.zimbra.cs.mailbox.DeltaSync.sync(DeltaSync.jav a:124)
at com.zimbra.cs.mailbox.DeltaSync.sync(DeltaSync.jav a:89)
at com.zimbra.cs.mailbox.MailboxSync.sync(MailboxSync .java:192)
at com.zimbra.cs.mailbox.ZcsMailbox.sync(ZcsMailbox.j ava:124)
at com.zimbra.cs.service.offline.OfflineSync.handle(O fflineSync.java:55)
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:303)
at com.zimbra.soap.SoapServlet.doPost(SoapServlet.jav a:217)
at javax.servlet.http.HttpServlet.service(HttpServlet .java:725)
at com.zimbra.cs.servlet.ZimbraServlet.service(Zimbra Servlet.java:206)
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:585)
at org.mortbay.jetty.HttpConnection$RequestHandler.co ntent(HttpConnection.java:988)
at org.mortbay.jetty.HttpParser.parseNext(HttpParser. java:756)
at org.mortbay.jetty.HttpParser.parseAvailable(HttpPa rser.java:218)
at org.mortbay.jetty.HttpConnection.handle(HttpConnec tion.java:415)
at org.mortbay.io.nio.SelectChannelEndPoint.run(Selec tChannelEndPoint.java:429)
at org.mortbay.thread.BoundedThreadPool$PoolThread.ru n(BoundedThreadPool.java:451)
Caused by: java.io.IOException: chunked stream ended unexpectedly
at org.apache.commons.httpclient.ChunkedInputStream.g etChunkSizeFromInputStream(ChunkedInputStream.java :252)
at org.apache.commons.httpclient.ChunkedInputStream.n extChunk(ChunkedInputStream.java:221)
at org.apache.commons.httpclient.ChunkedInputStream.r ead(ChunkedInputStream.java:176)
at java.io.FilterInputStream.read(Unknown Source)
at org.apache.commons.httpclient.AutoCloseInputStream .read(AutoCloseInputStream.java:108)
at java.io.FilterInputStream.read(Unknown Source)
at java.util.zip.InflaterInputStream.fill(Unknown Source)
at java.util.zip.InflaterInputStream.read(Unknown Source)
at java.util.zip.GZIPInputStream.read(Unknown Source)
at com.zimbra.common.util.tar.TarBuffer.readBlock(Tar Buffer.java:257)
at com.zimbra.common.util.tar.TarBuffer.readRecord(Ta rBuffer.java:223)
at com.zimbra.common.util.tar.TarInputStream.read(Tar InputStream.java:349)
at com.zimbra.common.util.CopyInputStream.read(CopyIn putStream.java:70)
at java.io.InputStream.read(Unknown Source)
at com.zimbra.cs.store.BlobBuilder.append(BlobBuilder .java:127)
at com.zimbra.cs.store.file.FileBlobStore.storeIncomi ng(FileBlobStore.java:94)
at com.zimbra.cs.store.StoreManager.storeIncoming(Sto reManager.java:112)
at com.zimbra.cs.mailbox.InitialSync.saveMessage(Init ialSync.java:1300)
... 37 more

Our zimbra server is running on 443. So our apache server gets these requests and passes the requests to the zimbra server (apache reverse proxy). Zimbra server is not running zimbraproxy (forget the exact name of the module). Web, admin console and everything else works fine, not zdesktop.