WrkStat page error

Question

I have a problem with WrkStat page. When the workflow is in running state I have the following exception:

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.

Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.

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:

[NullReferenceException: Object reference not set to an instance of an object.]
Microsoft.SharePoint.Publishing.CachedListItem.GetWorkflowInfo(SPListItem item) +878
Microsoft.SharePoint.Publishing.CachedListItem..ctor(SPListItem item, SPListItem alternateItem, NodeTypes nodeType, String id, String parentId, CachedUserResource title, String url, CachedUserResource description, CachedObjectFactory factory, List1& fieldInfo) +3785
Microsoft.SharePoint.Publishing.CachedListItem.CreateCachedListItem(SPListItem item, SPListItem alternateItem, Boolean parentIsWeb, CachedObjectFactory factory, List1& fieldInfo) +650
Microsoft.SharePoint.Publishing.CachedObjectFactory.CreateListItemFromUrl(String url, SPWeb contextWeb, Boolean enableCheckedOutItem) +802
Microsoft.SharePoint.Publishing.WebControls.ConsoleUtilities.get_ContextualListItemCached() +145 Microsoft.SharePoint.Publishing.WebControls.ConsoleContext.get_CurrentItemVersion() +9 Microsoft.SharePoint.Publishing.WebControls.ConsoleDataSource.retrieveItemVersion() +46 Microsoft.SharePoint.Publishing.WebControls.ConsoleDataSource.OnLoad(EventArgs e) +90
Microsoft.SharePoint.Publishing.WebControls.XmlConsoleDataSource.OnLoad(EventArgs e) +201
Microsoft.SharePoint.Publishing.WebControls.PublishingSiteActionsMenuCustomizer.OnLoad(EventArgs e) +186 System.Web.UI.Control.LoadRecursive() +66
System.Web.UI.Control.LoadRecursive() +191
System.Web.UI.Control.LoadRecursive() +191
System.Web.UI.Control.LoadRecursive() +191
System.Web.UI.Control.LoadRecursive() +191
System.Web.UI.Control.LoadRecursive() +191
System.Web.UI.Control.LoadRecursive() +191
System.Web.UI.Control.LoadRecursive() +191
System.Web.UI.Control.LoadRecursive() +191
System.Web.UI.Control.LoadRecursive() +191
System.Web.UI.Control.LoadRecursive() +191
System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +2428

But in other workflow states the page is shown correct. I use my custom task list whith several custom content types which have custom forms. The workflow is implemented in VS2010 and uses the create task with content type activity.

Any suggestion?

tnks