Outlook 2010 moaning about an Outlook 2007 issue! (Large contact group)

[googlemad]

One of our users has set up a contact group in their email account (Exchange 2010) which is made up of around 120 members, so nothing too mad. Whenever it is saved it then comes back either blank or 'This group contains more members than are supported when using Microsoft Office Outlook 2007 Service Pack 1 or an earlier version.'

 

Which would make sense, apart from we're using Office 2010 everywhere to begin with! Any ideas?