I created a workflow in SPD that works fine for me, but seems to cancel for anyone else even if the person has Full Control permissions.
This is the emailed error message: The workflow could not update the item, possibly because one or more columns for the item require a different type of information. From what I have been able to already troubleshoot, this is a pretty generic error. I've checked permissions on the Workflow tasks list. It seems to be a permission issue but I cannot figure out where.