Namespace exception

I'm getting the following exception on a web site hosted by Fasthosts. It's only recently started and is resolved by editing web.config thereby recycling the app. Problem is it comes back every 2 week or so. Any ideas anyone?

Exception Details: System.ArgumentException: The given name 'NHSSBS' matches at least two names in the collection object with different namespaces.

Source Error:

Line 32: string pageDatabasePath = SiteStructure.GetDatabasePath(Request.AppRelativeCurrentExecutionFilePath);
Line 33:
Line 34: SubSonic.Query query = new SubSonic.Query("Metatag");
Line 35: query.QueryType = SubSonic.QueryType.Select;
Line 36: query.WHERE("Path", pageDatabasePath);

Source File: e:\DOMAINS\s\sbs.nhs.uk\user\htdocs\UserControls\HTMLHead.ascx.cs Line: 34

Stack Trace:

[ArgumentException: The given name 'NHSSBS' matches at least two names in the collection object with different namespaces.]
System.Data.DataTableCollection.get_Item(String name) +1770251
SubSonic.SqlDataProvider.GetTableSchema(String tableName, TableType tableType) in C:\Program Files\SubSonic\SubSonic 2.0.3\src\SubSonic\DataProviders\SqlDataProvider.cs:430
SubSonic.DataService.GetSchema(String tableName, String providerName, TableType tableType) in C:\Program Files\SubSonic\SubSonic 2.0.3\src\SubSonic\DataProviders\DataService.cs:426
SubSonic.DataService.GetTableSchema(String tableName, String providerName) in C:\Program Files\SubSonic\SubSonic 2.0.3\src\SubSonic\DataProviders\DataService.cs:440
SubSonic.Query.BuildTableSchema(String tableName, String providerName) in C:\Program Files\SubSonic\SubSonic 2.0.3\src\SubSonic\Sql Tools\Query.cs:497
SubSonic.Query.BuildTableSchema(String tableName) in C:\Program Files\SubSonic\SubSonic 2.0.3\src\SubSonic\Sql Tools\Query.cs:492
SubSonic.Query..ctor(String tableName) in C:\Program Files\SubSonic\SubSonic 2.0.3\src\SubSonic\Sql Tools\Query.cs:651
UserControls_HTMLHead.SetupMetatags() in e:\DOMAINS\s\sbs.nhs.uk\user\htdocs\UserControls\HTMLHead.ascx.cs:34
UserControls_HTMLHead.Page_Load(Object sender, EventArgs e) in e:\DOMAINS\s\sbs.nhs.uk\user\htdocs\UserControls\HTMLHead.ascx.cs:27
System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e) +14
System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e) +35
System.Web.UI.Control.OnLoad(EventArgs e) +99
System.Web.UI.Control.LoadRecursive() +50
System.Web.UI.Control.LoadRecursive() +141
System.Web.UI.Control.LoadRecursive() +141
System.Web.UI.Control.LoadRecursive() +141
System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +627