I am using Zimbra since years and use the search function extensivly. The advanced search through the menu doesnot work as well. The quotes where made my zimbra advances search, not by me.
A somle search from: tanzer leads to:
msg: system failure: Caught null
query: "from: tanzer",
name: "ZimbraWebClient - FF3.0 (Linux)",
I restarted zimbra and tried again:
in:inbox from: tanzer
No errors, the GUI shows the normal mailbox.