SqlServer 2008 R2 Error 18456 with AD groups

We successfully performed a fresh install of Windows Server 2008 R2 and Windows SQL 2008 R2 Enterprise x64. 
However, I'm seeing the following issue when logging into the server via AD group (for our developers) using Windows Authentication.
Error: 18456, Severity: 14, State: 11
What does work:
1. Logging in directly with the admin (sa) account.
2. Adding a domain account directly (e.g. domain01\jsmith) in SqlServer.
3. Adding a domain account into a local group on the server, then adding the local group to SqlServer.
 
What does NOT work:
1. Adding a domain group (e.g. domain01\group1) in SqlServer.  It accepts the group fine, but we get the 18456 error when logging in.
2. Adding a domain group to a local group.  Then adding that local group to SqlServer.  It accepts the group, but we get the 18456 error when logging in.
3. Running SSMS as admin.  Our users don’t have permissions to run as Administrator.

I've been reading some pages/threads.
http://social.msdn.microsoft.com/Forums/en-US/sqlsetupandupgrade/thread/043898a3-eed8-4175-9be1-40bf1a2bdbaa
http://sqlblog.com/blogs/aaron_bertrand/archive/2011/01/14/sql-server-v-next-denali-additional-states-for-error-18456.aspx
http://www.cleverworkarounds.com/2010/08/01/sql-server-oddities/

This setup works fine on our Windows 2003 and SqlServer 2005 machine.  However, upgrading to Windows 2008/SqlServer 2008 is causing the situation.
Any advice would be appreaciated.