Hi mccureton,
Since you installed SQL Server Express edition and another SQL Server 2005 edition on the same mahcine, this issue can be caused by VS.NET points to the default SQL server instance instead of the Express edition. Hence, please go to check the following settings:
Tools | Options | Database Tools | Data Connections | SQL Server Instance Name
Tools | Options | Database Tools | Design-time Validation Database | SQL Server Instance Name
In addition, you probably need to confirm the ?user instances? feature of SQL Server Express edition is enabled.
Working with User Instances
http://msdn2.microsoft.com/en-us/library/ms254504(vs.80).aspx
Sincerely,
Benson Yu
Microsoft Online Community Support
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