We have a brand new installtion of Zimbra 7.1 on Ubuntu x64

IMAP Connection of Outlook and Thunderbird clients seems to be broken:

If we delete a Subfolder in a Shared Folder Thunderbird and Outlook is broken: The error Message is LSUB failed. In mailbox.log the following error message appears:

2011-06-30 09:49:42,809 WARN [ImapSSLServer-51] [name=user@domain.at;ip=910.113.220.140;] imap - LSUB failed
com.zimbra.cs.mailbox.MailServiceException$NoSuchI temException: no such folder path: /NurZumImapTesten/Ordner1
ExceptionId:ImapSSLServer-51:1309420182809:0655abbe3e91af42
Code:mail.NO_SUCH_FOLDER Argpath, STR, "/NurZumImapTesten/Ordner1")
at com.zimbra.cs.mailbox.MailServiceException.NO_SUCH _FOLDER(MailServiceException.java:185)
at com.zimbra.cs.mailbox.Mailbox.getFolderByPath(Mail box.java:2962)
at com.zimbra.cs.imap.ImapPath.getFolder(ImapPath.jav a:315)
at com.zimbra.cs.imap.ImapPath.getFolder(ImapPath.jav a:310)
at com.zimbra.cs.imap.ImapPath.isVisible(ImapPath.jav a:548)
at com.zimbra.cs.imap.ImapHandler.checkSubscription(I mapHandler.java:1947)
at com.zimbra.cs.imap.ImapHandler.doLSUB(ImapHandler. java:1919)
at com.zimbra.cs.imap.ImapHandler.executeRequest(Imap Handler.java:500)
at com.zimbra.cs.imap.TcpImapHandler.processCommand(T cpImapHandler.java:98)
at com.zimbra.cs.tcpserver.ProtocolHandler.processCon nection(ProtocolHandler.java:197)
at com.zimbra.cs.tcpserver.ProtocolHandler.run(Protoc olHandler.java:140)
at java.util.concurrent.ThreadPoolExecutor$Worker.run Task(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run (ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:662)
At this Point Thunderbird and Outlook is no longer able to mount ANY IMAP Folder except Inbox and Trash?!?

What is going on?!? Are there Traces of this Folders left somewhere? Is IMAP implementation broken?!?

If i recreate this previous deleted Folder Thunderbird and Outlook are working again but this would imply that i can never ever delete a shared folder again?!?

PLEASE HELP!: