Sql Instance Error After Upgrading To Express Advanced

[Background]
Upgraded SQL Server Express to Advanced and I started getting a user instance error. I followed the advice on some posts (most notably: http://blogs.msdn.com/sqlexpress/). I deleted the User Template Data as the instructions say but now get the error below when trying to run my application.
I've tried setting User Instance = False with no luck. Also noticed after rebooting that the Template Data file was recreated but the folder is empty. Have tried re-installing the update but it says there's nothing to update! Has anyone else had this problem? Any fixes? Any help will be greatly appreciated...

Many thanx,
Milt

The details:

Failed to generate a user instance of SQL Server due to a failure in copying database files. The connection will be closed.



Description: An
unhandled exception occurred during the execution of the current web
request. Please review the stack trace for more information about the
error and where it originated in the code.



Exception Details: System.Data.SqlClient.SqlException:
Failed to generate a user instance of SQL Server due to a failure in
copying database files. The connection will be closed.



Source Error:






Line 88: /// <returns></returns>
Line 89: public static ShoppingCart GetCart() {
Line 90: IDataReader rdr = ShoppingCartProvider.Instance.CartGetCurrentCart(GetUserName());
Line 91: ShoppingCart cart = new ShoppingCart();
Line 92: cart.Load(rdr);








Source File: c:2.0LineFLowDEVSHED1production1_catherinetough.co.ukCathyTProductionSiteApp_CodeBLLShoppingCartManager.cs Line: 90




Stack Trace:






[SqlException (0x80131904): Failed to generate a user instance of SQL Server due to a failure in copying database files. The connection will be closed.]
System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection) +171
System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj) +199
System.Data.SqlClient.TdsParser.Run(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj) +2300
System.Data.SqlClient.SqlInternalConnectionTds.CompleteLogin(Boolean enlistOK) +34
System.Data.SqlClient.SqlInternalConnectionTds.OpenLoginEnlist(SqlConnection owningObject, SqlConnectionString connectionOptions, String newPassword, Boolean redirectedUserInstance) +606
System.Data.SqlClient.SqlInternalConnectionTds..ctor(DbConnectionPoolIdentity identity, SqlConnectionString connectionOptions, Object providerInfo, String newPassword, SqlConnection owningObject, Boolean redirectedUserInstance) +193
System.Data.SqlClient.SqlConnectionFactory.CreateConnection(DbConnectionOptions options, Object poolGroupProviderInfo, DbConnectionPool pool, DbConnection owningConnection) +218
System.Data.ProviderBase.DbConnectionFactory.CreatePooledConnection(DbConnection owningConnection, DbConnectionPool pool, DbConnectionOptions options) +28
System.Data.ProviderBase.DbConnectionPool.CreateObject(DbConnection owningObject) +429
System.Data.ProviderBase.DbConnectionPool.UserCreateRequest(DbConnection owningObject) +70
System.Data.ProviderBase.DbConnectionPool.GetConnection(DbConnection owningObject) +510
System.Data.ProviderBase.DbConnectionFactory.GetConnection(DbConnection owningConnection) +85
System.Data.ProviderBase.DbConnectionClosed.OpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory) +89
System.Data.SqlClient.SqlConnection.Open() +160
Microsoft.ApplicationBlocks.Data.SqlHelper.ExecuteReader(String connectionString, CommandType commandType, String commandText, SqlParameter[] commandParameters) +196
Commerce.Providers.SqlShoppingCartProvider.CartGetCurrentCart(String userName) in D:@My ProjectsPayPalCommerce Template 2.0CommerceStarterKit09Commerce.ShoppingCartProviderSqlShoppingCartProvider.cs:139

[Exception: Error Executing CMRC_CART_GetCurrentCart: Failed to generate a user instance of SQL Server due to a failure in copying database files. The connection will be closed.
@userName=9fb1c091-5117-4988-8592-19940069dc1e
]
Commerce.Providers.SqlShoppingCartProvider.HandleError(SqlParameter[] paramArray, SqlException x, String sprocName) in D:@My ProjectsPayPalCommerce Template 2.0CommerceStarterKit09Commerce.ShoppingCartProviderSqlShoppingCartProvider.cs:270
Commerce.Providers.SqlShoppingCartProvider.CartGetCurrentCart(String userName) in D:@My ProjectsPayPalCommerce Template 2.0CommerceStarterKit09Commerce.ShoppingCartProviderSqlShoppingCartProvider.cs:141
ShoppingCartManager.GetCart() in c:2.0LineFLowDEVSHED1production1_catherinetough.co.ukCathyTProductionSiteApp_CodeBLLShoppingCartManager.cs:90
MiniBasket.Page_Load(Object sender, EventArgs e) in c:2.0LineFLowDEVSHED1production1_catherinetough.co.ukCathyTProductionSiteModulesMiniBasket.ascx.cs:17
System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e) +13
System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e) +45
System.EventHandler.Invoke(Object sender, EventArgs e) +0
System.Web.UI.Control.OnLoad(EventArgs e) +80
System.Web.UI.Control.LoadRecursive() +49
System.Web.UI.Control.LoadRecursive() +132
System.Web.UI.Control.LoadRecursive() +132
System.Web.UI.Control.LoadRecursive() +132
System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +3745











Version Information: Microsoft .NET Framework Version:2.0.50727.42; ASP.NET Version:2.0.50727.42