I'm experiencing a wierd, intermittent sort of error that seems to happen mostly when my ASP.Net app has been idle for a few minutes:

"Server Error in '/PHfusin' Application.
Object reference not set to an instance of an object.
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."

The stack trace looks as follows:

[NullReferenceException: Object reference not set to an instance of an object.]
OakLeaf.MM.Main.Business.mmBusinessObject.SetCurrentDataSet(DataSet ds)
PHfusion.PHfFramework.Business.phfBusinessObject.SetDataSet(DataSet ds)
PHfusion.PHfWeb.Message.MessageSummary.Page_Load(Object sender, EventArgs e)
System.EventHandler.Invoke(Object sender, EventArgs e) +0
System.Web.UI.Control.OnLoad(EventArgs e) +67
System.Web.UI.Control.LoadRecursive() +35
System.Web.UI.Page.ProcessRequestMain() + 731

The message makes it looks as if my ancestor object (mmBusinessObject) has been lost completely, and I have no idea how that could be happening. And I can restart the application, repeat the exact same steps a second time and NOT see this error.

Has anyone experienced similar problems? I'd appreciate any advice.