New SQL Server Install Mixed Mode authentication not allowing Windows Authentication

I have a new instance of SQL Server 2008 RS Standard Edition. I enabled Mixed-Mode Authentication but I can't get Windows Authentication to work. I get the Er开发者_C百科ror: 18456, Login Failed for user 'MyDomain\jreddy'. I can log in with the sa account so I can make changes, but I'm not sure what to change. Any help would be greatly appreciated.

I've checked the event log and found this error relating to the login failure:

Reason: Token-based server access validation failed with an infrastructure error.

When you enable Windows Authentication for Sql Server, it won't just automatically resolve authentication requests with Active Directory. You still have to set up an account for each user, and assign Sql Server permissions to that account for individual databases (often done via roles). The good news is that you can often do this for an entire Active Directory group at a time — for example, an unusually permissive database might allow the entire MyDomain\Users to log in and use a specific database.

Apparently the problem was with UAC on the Windows 2008 server. Our network guys were changing some group policies and turned UAC on for all our servers. So, this had nothing to do with switching edition of SQL Server (Ent --> Standard). Turning off UAC fixed the issue I was having.