A customer of mine was playing around with Approval workflow. A problem she encountered was that some of her collagues have been unable to edit document. The only option that was visible in Word 2007 was: „Edit this task“ (figure 1).
Figure 1. – Editing a task from Word 2007 interface
The solution to this problem is fairly simple: All users that participate in an Approval workflow (or any other workflow) must have an appropriate permission. To approve something users must be in an appropriate group or you must give them Approve permission (figure 2).
Figure 2. – Adding new user with proper permissions
The „problem“ here was that Sharepoint will allow you to assign a task to an user that cannot approve your document.