Downloading offline address book in Outlook deletes contents of .nk2 file

Selected users are connected to a Windows Server 2008 R2 running Remote Desktop Services, with Office 2007.  When they select Tools, Send/Receive, Download Address Book (Full Details) within Outlook, the process also deletes the contents of their .nk2 file.  How can I download the updated Offline Address Book without it removing the contents of their .NK2 file ??

Thank you,

David