When I try to create an Approval workflow on this one document library (I've tried to do it both custom from SPD and OOB), I cannot open the tasks. I get all kinds of errors. When I try to open the task, when I try to open the task from the generated email, when I try to make changes to the task in datasheet view, all Correlation ID errors. The only information I have gotten from SharePoint is:
"Invalid WorkflowInstanceID parameter in URL"
and in the logs it says that parameter is null.
Does anybody know what this could be?