Hi!

We have an additional Windows 2008 DC in a branch connected to Head Office Main DC through VPN. Many of our users is branch office are having problem logging on to domain and getting message "Trust Relationship Failed" frequently. We have to disjoin and rejoin them to the domain.

Any Suggestions?

Thanks.

Were these computers out of contact with the domain controller for more than 30 days? Computers have passwords that by default update every 30 days with AD. Often when computers, especially laptops, are outside of the corporate network for more than 30 days this will happen. This link may lead to you to some ways to test this. YOu can reset without rejoin by using netdom however it is not installed by default on workstations.  You can also test with powershell using 'Test-ComputerSecureChannel -repair'