Constant Sync Attempt after Too-Large Briefcase Upload

[aferrer]

A few hours ago, I attempted to upload a file to a briefcase that (I didn't realize at the time) was over the maximum size. I tried to cancel the upload, but the dialog box wouldn't close, so I quit and restarted Zimbra Desktop. Ever since, ZD has been constantly attempting to sync my account, but never downloads new mail nor gives me any error message--just tells me that a sync is running. I also can't log in to the advanced webmail, though I can access the plain HTML webmail.

Any ideas on how to force stop the sync or otherwise get my full Zimbra access back up and running?