I have an installation of DNN5.0.1 and have installed the blog module 3.5.1.

I add the module to the home page content area and I can then see 5 modules added to the page. However, a critical error shows and I can not do anything with the modules except delete them. In the event log the following error is recorded for each of the modules. The error shows that it can't connect to the SQL server which is very odd. The rest of the site is working OK and there is only a single SQL 2008 Express database being used for the site.

Does anyone have any idea what the problem might be?

Message: System.Data.SqlClient.SqlException: A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: SQL Network Interfaces, error: 26 - Error Locating Server/Instance Specified) at System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection) at System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj) at System.Data.SqlClient.TdsParser.Connect(ServerInfo serverInfo, SqlInternalConnectionTds connHandler, Boolean ignoreSniOpenTimeout, Int64 timerExpire, Boolean encrypt, Boolean trustServerCert, Boolean integratedSecurity, SqlConnection owningObject) at System.Data.SqlClient.SqlInternalConnectionTds.AttemptOneLogin(ServerInfo serverInfo, String newPassword, Boolean ignoreSniOpenTimeout, Int64 timerExpire, SqlConnection owningObject) at System.Data.SqlClient.SqlInternalConnectionTds.LoginNoFailover(String host, String newPassword, Boolean redirectedUserInstance, SqlConnection owningObject, SqlConnectionString connectionOptions, Int64 timerStart) at System.Data.SqlClient.SqlInternalConnectionTds.OpenLoginEnlist(SqlConnection owningObject, SqlConnectionString connectionOptions, String newPassword, Boolean redirectedUserInstance) at System.Data.SqlClient.SqlInternalConnectionTds..ctor(DbConnectionPoolIdentity identity, SqlConnectionString connectionOptions, Object providerInfo, String newPassword, SqlConnection owningObject, Boolean redirectedUserInstance) at System.Data.SqlClient.SqlConnectionFactory.CreateConnection(DbConnectionOptions options, Object poolGroupProviderInfo, DbConnectionPool pool, DbConnection owningConnection) at System.Data.ProviderBase.DbConnectionFactory.CreatePooledConnection(DbConnection owningConnection, DbConnectionPool pool, DbConnectionOptions options) at System.Data.ProviderBase.DbConnectionPool.CreateObject(DbConnection owningObject) at System.Data.ProviderBase.DbConnectionPool.UserCreateRequest(DbConnection owningObject) at System.Data.ProviderBase.DbConnectionPool.GetConnection(DbConnection owningObject) at System.Data.ProviderBase.DbConnectionFactory.GetConnection(DbConnection owningConnection) at System.Data.ProviderBase.DbConnectionClosed.OpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory) at System.Data.SqlClient.SqlConnection.Open() at Microsoft.ApplicationBlocks.Data.SqlHelperParameterCache.DiscoverSpParameterSet(SqlConnection connection, String spName, Boolean includeReturnValueParameter, Object[] parameterValues) at Microsoft.ApplicationBlocks.Data.SqlHelperParameterCache.GetSpParameterSetInternal(SqlConnection connection, String spName, Boolean includeReturnValueParameter) at Microsoft.ApplicationBlocks.Data.SqlHelperParameterCache.GetSpParameterSet(String connectionString, String spName, Boolean includeReturnValueParameter) at Microsoft.ApplicationBlocks.Data.SqlHelperParameterCache.GetSpParameterSet(String connectionString, String spName) at Microsoft.ApplicationBlocks.Data.SqlHelper.ExecuteReader(String connectionString, String spName, Object[] parameterValues) at DotNetNuke.Modules.Blog.Data.SqlDataProvider.GetBlogModuleSettings(Int32 PortalID, Int32 TabID) at DotNetNuke.Modules.Blog.Business.Utility.GetBlogModuleSettings(Int32 PortalID, Int32 TabID) at DotNetNuke.Modules.Blog.ViewBlog.Page_Init(Object sender, EventArgs e) at System.Web.UI.Control.OnInit(EventArgs e) at System.Web.UI.UserControl.OnInit(EventArgs e) at System.Web.UI.Control.InitRecursive(Control namingContainer) at System.Web.UI.Control.AddedControl(Control control, Int32 index) at System.Web.UI.ControlCollection.Add(Control child) at DotNetNuke.Modules.Blog.MainView.Page_Init(Object sender, EventArgs e) at System.Web.UI.Control.OnInit(EventArgs e) at System.Web.UI.UserControl.OnInit(EventArgs e) at System.Web.UI.Control.InitRecursive(Control namingContainer) at System.Web.UI.Control.AddedControl(Control control, Int32 index) at System.Web.UI.ControlCollection.Add(Control child) at DotNetNuke.UI.Modules.ModuleHost.InjectModuleContent(Control content) at DotNetNuke.UI.Modules.ModuleHost.CreateChildControls() at System.Web.UI.Control.EnsureChildControls() at DotNetNuke.UI.Modules.ModuleHost.get_ModuleControl() at DotNetNuke.UI.Containers.Container.get_ModuleControl() at DotNetNuke.UI.Containers.Container.ProcessModule() at DotNetNuke.UI.Skins.Pane.InjectModule(ModuleInfo objModule)
 

Well spotted Dario, thank you for that.

Paul