one of clients is getting local failure notices every 2 minutes.
He is using Outlook 2010, windows 7.
What could be the problem with this error: could not get/create the mailbox root folder?

Subject: Local Failure Notice
Importance: High

This e-mail was generated for technical support purposes.

Sync Type: Initial Sync

Sync Token (before request): no sync token

Computer Name: WEBDIR

ZCO Version: 6.0.6097.11

Server Version: 6.0.12_GA_2883

Error IDs:
id (11) type(folder) message(could not get/create the mailbox root folder)