I am having a weird issue with a user in our SharePoint farm. When you see the users name within SharePoint the URL sharepoint tries to go to is
This was correct and is correct on our test server. Somehow that ID no longer exists and a new one has been created. So the URL should now be
On new items the user creates or modifies the link is fine and when you click on his name you are taken to the correct profile page. On old items if you click on the name you get given a SharePoint error.
My question is how can I force SharePoint to update this ID? In both cases the users display name is correct.