I have SQL Server 2008 installed on my machine and use SSMS to manage remote 2008 and 2000 databases. I recently tried to create a diagram on a local instance of SQL and get this error “Unspecified error (MS Visual Database Tools). I have VS 2010 and APEXSQL tools installed. I finally gave up and reloaded Windows 7 and all the dev tools and it worked for a day them started giving me this error again.

Where I click on details this is what I get:
===================================
Unspecified error (MS Visual Database Tools)
—————————— Program Location:
at
System.Runtime.InteropServices.Marshal.ThrowExceptionForHRInternal(Int32
errorCode, IntPtr errorInfo) at
Microsoft.SqlServer.Management.UI.VSIntegration.NativeMethods.ThrowOnFailure(Int32
hr) at
Microsoft.SqlServer.Management.UI.VSIntegration.Editors.VirtualProject.CreateDesigner(Urn
origUrn, DocumentType editorType, DocumentOptions aeOptions,
IManagedConnection con, String fileName) at
Microsoft.SqlServer.Management.UI.VSIntegration.Editors.VirtualProject.Microsoft.SqlServer.Management.UI.VSIntegration.Editors.ISqlVirtualProject.CreateDesigner(Urn
origUrn, DocumentType editorType, DocumentOptions aeOptions,
IManagedConnection con, String fileName) at
Microsoft.SqlServer.Management.UI.VSIntegration.Editors.ISqlVirtualProject.CreateDesigner(Urn
origUrn, DocumentType editorType, DocumentOptions aeOptions,
IManagedConnection con, String fileName) at
Microsoft.SqlServer.Management.UI.VSIntegration.Editors.ScriptFactory.CreateDesigner(DocumentType
editorType, DocumentOptions aeOptions, Urn parentUrn,
IManagedConnection mc, String fileName) at
Microsoft.SqlServer.Management.UI.VSIntegration.Editors.VsDocumentMenuItem.CreateDesignerWindow(IManagedConnection
mc, DocumentOptions options)
Did some more research. The guy in this post said that he was having the same problem and ApexSQL Tools was the culprit. Try uninstalling ApexSQL Tools, and if that resolves the issue, I’d be contacting ApexSQL to see if they have a fix for the problem.