I had a problem with a migrated user from Exchange 2003 to Exchange 2007 not showing the correct version number. It was not listed as Legacy Mailbox and it resided on a Exchange 2007 store. Running the get-mailbox command I saw that the version number on the mailbox was 0.0 and not 0.1 for Exchange 2007. Because of the mailbox being in this state the user could not connect to OWA. I got the following message:
Inner Exception Exception type: Microsoft.Exchange.Data.Directory.InvalidADObjectOperationException Exception message: Property Languages cannot be set on this object because it requires the object to have version 0.1 (8.0.535.0) or later. Current version of the object is 0.0 (6.5.6500.0).
To resolve this problem you need to correct the properties of the mailbox. Do this by running the following commandlet in Exchange Management Shell:
Set-Mailbox -Identity <user> -ApplyMandatoryProperties
View KB 931747 article over at Microsoft Support, http://support.microsoft.com/kb/931747