A couple of people have reported running into the following problem after installing the performance patch we recently made available ( see this post for details ):

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Microsoft Visual Studio
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Could not locate entry in sysdatabases for database '<your database name plus a long number>'. No entry found with that name. Make sure that the name is entered correctly.
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OK   Cancel  
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Please make sure that your SQL Server instance is not running as the Network Service account. When you try and create a project in the default path ( documents & settings ), you will have this problem if the SQL Server instance we use for design time validation is not running against the Local System or Domain account. Let me hilite the appropriate section in the readme:

After installing via the MSI you need to make sure that the SQL Server instance that is used for design time verification is running under a security account that has access to your project folder; you can change it to either LocalSystem or to the users machine or domain account. To change this, you need to use the SQL Server Configuration Manager, available through Start | Programs | Microsoft SQL Server 2005 | Configuration Tools | SQL Server Configuration Manager.

NOTE: Do not use the Windows Service Manager, since that will not change the ACL’s on the Registry correctly for SQL Server.

After this you need to login to SQL Server as a sysadmin role member and run:

use master
go
grant execute on sp_detach_db to public
go

<SNIP>

Hope that helps!