I am having some intermittent issues with the store lately adding products.  I am using store 5.1.  Any thoughts?

AssemblyVersion: 04.04.01
PortalID: 0
PortalName: Facets, Ltd.
UserID: 11
UserName: Joseph
ActiveTabID: 57
ActiveTabName: Products
RawURL: /StoreAdministration/Products/tabid/57/ctl/maindata/mid/373/Default.aspx
AbsoluteURL: /Default.aspx
AbsoluteURLReferrer: http://www.facetsltd.com/StoreAdministration/Products/tabid/57/ctl/maindata/mid/373/Default.aspx
UserAgent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.3) Gecko/20070309 Firefox/2.0.0.3
DefaultDataProvider: DotNetNuke.Data.SqlDataProvider, DotNetNuke.SqlDataProvider
ExceptionGUID: 3f29f01b-602f-40c5-bbc6-c012a278c29c
InnerException: Object reference not set to an instance of an object.
FileName:
FileLineNumber: 0
FileColumnNumber: 0
Method: CATALooK._URLControl.get_Url
StackTrace:
Message: DotNetNuke.Services.Exceptions.PageLoadException: Object reference not set to an instance of an object. ---> System.NullReferenceException: Object reference not set to an instance of an object.at CATALooK._URLControl.get_Url()at CATALooK.ProductMainData.btnAddProduct_Click(Object sender, EventArgs e)at System.Web.UI.WebControls.LinkButton.OnClick(EventArgs e)at System.Web.UI.WebControls.LinkButton.RaisePostBackEvent(String eventArgument)at System.Web.UI.WebControls.LinkButton.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument)at System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument)at System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData)at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)--- End of inner exception stack trace ---
Source:
Server Name: WSS17