Many Windows users have reported that their ZD suddenly stopped working after running a Windows Defender update. A fixed was first posted by
capill@orionhealth.com here:
[SOLVED] Couldn't Access Zimbra Desktop Server
It's also reported that a later defender update fixed the problem. But just in case you have to manually correct it, here is how:
1) Use Notepad to open %systemroot%\system32\drivers\etc\hosts (e.g. c:\windows\system32\drivers\etc\hosts)
2) make sure you have this line; if not, add it and save the file
Code:
127.0.0.1 localhost
3) Control Panel->Administrative Tools->Services->Yahoo! Zimbra Desktop Service->restart (or just reboot your machine if you are not sure how to manually restart a service)
Link to web coverage over this defender mistake:
Windows Defender: False alarm triggered by hosts file - News - The H Security: News and features