KB Article: http://support.microsoft.com/kb/2665724

INTRODUCTION

Consider the following scenario:

  • You use a smart card to log on to a computer.
  • You sign in to Microsoft Office Communicator 2007.
  • You lock the computer, and then you remove the smart card.
  • You insert the smart card and unlock the computer after more than 10 hours.

In this scenario, Office Communicator 2007 disconnects from the server. Additionally, you receive a message that asks you to type your credentials.