exchange 2010 sp2: one user's unread folder language is different

we have exchange server 2010 SP2. one of our new employee while logging into owa for the first time selected arabic as language. then he informed me that he needs it as english. I changed them back to english from his regional settings. then all changed to english except favourite folders his inbox,calenders, contact , task all in arabic. Then i used the following cmdlets

Set-MailboxRegionalConfiguration -Identity "user" -Language en-US -LocalizeDefaultFolderName:$true -DateFormat "M/d/yyyy" -TimeFormat "hh:mm tt" -TimeZone "Arabian Standard Time"

Then all folders become english except folder "unread"

only this one shows in arabic