Invalid/Inactive status Close - In Progress in statement Close error message in change workflow

Invalid/Inactive status Close - In Progress in statement Close error message in change workflow

upgraded to 12000, 
While trying to edit the change workflow, if i open the workflow and click on save i get this error message,
without any modification or change. 

' Invalid/Inactive status Close - In Progress in statement Close."
what does it mean in English and how to fix it.

but page cannot be displayed