Umbraco v 4.11.8 (Assembly version: 1.0.4869.17899), SQL Server 2008 R2, Win 7

Hi,

When I attempt to create a new node I get the following:

Server Error in '/' Application.

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The SqlParameter is already contained by another SqlParameterCollection.
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.ArgumentException: The SqlParameter is already contained by another SqlParameterCollection.
Source Error: 

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace: 

[ArgumentException: The SqlParameter is already contained by another SqlParameterCollection.] System.Data.SqlClient.SqlParameterCollection.Validate(Int32 index, Object value) +5286953 System.Data.SqlClient.SqlParameterCollection.AddRange(Array values) +250 StackExchangeContrib.Profiling.SqlHelpers.SqlServer.ProfiledSqlServerHelper.ExecuteNonQuery(String commandText, SqlParameter[] parameters) +329 umbraco.DataLayer.SqlHelper`1.ExecuteNonQuery(String commandText, IParameter[] parameters) +143 [SqlHelperException: Umbraco Exception (DataLayer): SQL helper exception in ExecuteNonQuery] umbraco.DataLayer.SqlHelper`1.ExecuteNonQuery(String commandText, IParameter[] parameters) +318 umbraco.BusinessLogic.Permission.MakeNew(User User, CMSNode Node, Char PermissionKey) +471 umbraco.cms.businesslogic.CMSNode.MakeNew(Int32 parentId, Guid objectType, Int32 userId, Int32 level, String text, Guid uniqueID) +1773 umbraco.cms.businesslogic.web.Document.MakeNew(String Name, DocumentType dct, User u, Int32 ParentId) +515 umbraco.contentTasks.Save() +152 umbraco.presentation.create.dialogHandler_temp.Create(String NodeType, Int32 TypeId, Int32 NodeId, String Text) +586 umbraco.cms.presentation.create.controls.content.doCreation() +199 umbraco.cms.presentation.create.controls.content.sbmt_Click(Object sender, EventArgs e) +34 System.Web.UI.WebControls.Button.OnClick(EventArgs e) +9552602 System.Web.UI.WebControls.Button.RaisePostBackEvent(String eventArgument) +103 System.Web.UI.WebControls.Button.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument) +10 System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) +13 System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) +35 System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +1724

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Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.0.30319.18044

I've tried the usual tricks so worried that there is something seriously wrong with my database. Any pointers as to what else I could try would be massively appreciated.

Thanks

Bill