I have 6 users in a branch office
There is a VPN connection between our offices.
Our exchange 2010 server is hosted in our head office
The branch office computers are installed with Office 2010, they are connected to the domain.
Randomly, since Thursday Outlook has been persistently requesting these users to enter their username and password.
Their user accounts are not disabled, the passwords have not expired, the VPN is on and working.
They have restarted their computers, I have restarted their local DC but the issue is still occurring. I have also deleted and re-created user profiles in Outlook to no avail.
DC is Windows Server 2008 R2,
Exchange is 2010 SP2 on Server 2008 R2
Does anyone know what could be causing this?