Error 916 : The server principal “username” is not able to access the database “database_name” under the current security context.

I got below error when trying to connect to my database using SQL Server Management Studio 2008. 


The server principal “username” is not able to access the database “database_name” under the current security context. (Microsoft SQL Server, Error: 916)


This error can be encountered when connecting to either SQL Server 2005 or 2008 databases using SQL Server 2008 Management Studio. 
The error itself indicates the problem that connecting to a database that you do not own.


This issue is fixed and already released in SQL Server 2008 SP1. Please install it for the fix.
Please try using the following workaround without installing SQL Server 2008 SP1 and let us know if that helps:

• Bring Object Explorer Details window by clicking on “View” in the Menu bar –> Select “Object Explorer Details” in menu (or hitting F7)
• In Object Explorer window click at Databases folder
• In Object Explorer Details window right-click at the column header and deselect “Collation”
• Refresh Databases folder in Object Explorer.

If the issue is not solved, uncheck the following items:
-Size (MB)
-Database Space Used (KB)
-Index Space Used (KB)
-Space Available (KB)
-Default File Group
-Mail Host
-Collation


Ref: http://sql.widestuff.com/?p=168