Have you every received this message when you try to access Database Diagrams for SQL Server?
If so, there is a simple fix. You need to change to ownership of the database to a valid user on the computer that you are using like so:
EXEC sp_dbcmptlevel ‘<database-name>’, ’90’
ALTER AUTHORIZATION ON DATABASE::<database-name> TO “<valid-domain-and-user>”
EXECUTE AS USER = N’dbo’ REVERT
Replace the text <database-name> with the name of the database that you can’t access the database diagrams for and also replace the text <valid-domain-and-user> with a valid entry such as: RUSS-LAPTOP\Russ.
This worked a treat for me and hopefully it will for you too. If it doesn’t then you can also try the following to check the compatibility level and the db owner
1. Right Click on your database, choose Properties
2. Goto the Options Page
3. In the Dropdown at right labeled “Compatibility Level” choose “SQL Server 2005(90)”
4. Goto the Files Page
5. Enter “sa” in the owner textbox
6. Press OK and retry