I am getting the following error when trying to login to one of our SQL servers with Windows Authentication with the TCP protocol (named pipes works fine):

18452,"28000",[Microsoft][ODBC SQL Server Driver][SQL Server]Login failed for user '(null)'. Reason: Not associated with a trusted SQL Server connection.

The issue only arises when connecting from some workstations. In other words, user A can login from Computer 1 but not from computer 2. User A was logged in the same windows login from both computers.

We recently updated from an NT domain to Active Directory about a month ago. The problem just started appearing last Friday.

SQL Server SP3
Mixed Authentication