Worklfow Task Approval reminder still emailing for Deleted Document

Hi,

We have a user that is receiving email reminders for an Approval Task on a document that was deleted 6 months ago.

We have checked the Recycle Bin, Site Collection Bin and 2nd stage and the document is no longer in any of those.

We checked the Workflow History list https://mysite/sites/mysitecollection/lists/Workflow%20History but found no entry there.

The email has links to the document and  to the approval tasks but when you click either of them it take us to the Item not Found page.

Is there another list i can check for approval reminders, something i might have missed?

Thanks,

Mark