I've created a new DataType that allows you to select a parent Node and, when the DataType is added to a particular document type, if you create a content node of that document type, you can select any associated nodes using this new DataType.

For example, let's assume I have a product repository with a list of products associated under it.  I want to create a new coupon repository and when I add a coupon, I want to select which products apply to the coupon.  The products list may change, so having this association is important.

The datatype was working fine, but I recently tried it in different Umbraco 4.7 and 4.8 installations and every time it's crashing the IIS App Pool.  The stack trace is below.  It's very important I get this working.  I'd be happy to add the source code but it based on Tim Geyssens samples (for example: http://www.nibble.be/?p=90).  Any help is GREATLY appreciated!!

Event code: 3005 
Event message: An unhandled exception has occurred. 
Event time: 8/13/2012 11:18:21 AM 
Event time (UTC): 8/13/2012 3:18:21 PM 
Event ID: 8bc97c5c4e1643008e02455206e226b5 
Event sequence: 131 
Event occurrence: 1 
Event detail code: 0 
 
Application information: 
    Application domain: /LM/W3SVC/11/ROOT-1-129893446159694375 
    Trust level: Full 
    Application Virtual Path: / 
    Application Path: C:\inetpub\wwwroot\umbraco\ 
    Machine name: WEBSITETEST 
 
Process information: 
    Process ID: 2056 
    Process name: w3wp.exe 
    Account name: IIS APPPOOL\knowledgebase 
 
Exception information: 
    Exception type: SqlHelperException 
    Exception message: Umbraco Exception (DataLayer): SQL helper exception in ExecuteNonQuery
   at umbraco.DataLayer.SqlHelper`1.ExecuteNonQuery(String commandText, IParameter[] parameters)
   at umbraco.BasePages.BasePage.ClearLogin()
   at System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e)
   at System.EventHandler.Invoke(Object sender, EventArgs e)
   at umbraco.BasePages.BasePage.OnLoad(EventArgs e)
   at System.Web.UI.Control.LoadRecursive()
   at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
Timeout expired.  The timeout period elapsed prior to obtaining a connection from the pool.  This may have occurred because all pooled connections were in use and max pool size was reached.
   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.SqlHelper.ExecuteNonQuery(String connectionString, CommandType commandType, String commandText, SqlParameter[] commandParameters)
   at umbraco.DataLayer.SqlHelper`1.ExecuteNonQuery(String commandText, IParameter[] parameters)
 
 
Request information: 
    Request URL: http://websitetest:9080/umbraco/logout.aspx?redir=/umbraco/developer/datatypes/editDataType.aspx?id=1103 ;
    Request path: /umbraco/logout.aspx 
    User host address: 192.168.1.243 
    User:  
    Is authenticated: False 
    Authentication Type:  
    Thread account name: IIS APPPOOL\umbraco 
 
Thread information: 
    Thread ID: 16 
    Thread account name: IIS APPPOOL\umbraco 
    Is impersonating: False 
    Stack trace:    at umbraco.DataLayer.SqlHelper`1.ExecuteNonQuery(String commandText, IParameter[] parameters)
   at umbraco.BasePages.BasePage.ClearLogin()
   at System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e)
   at System.EventHandler.Invoke(Object sender, EventArgs e)
   at umbraco.BasePages.BasePage.OnLoad(EventArgs e)
   at System.Web.UI.Control.LoadRecursive()
   at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)