After approving a task, user is taken to the task list

Hi All,

We have a problem that only seems to apply to some of our users, which I guess suggests a client issue.

When a task email is sent and the user clicks on 'Open/Edit this task' (Outlook 2010/2007), they follow the link and approve the task.  When they have approved the task, it takes the user to the Workflow Tasks list rather than just closing the modal approval box.   It does not affect all users, though it does appear to be our German users who experience the problem and not our UK users; the UK people get the expected behaviour (i.e. modal box closing).

Can anyone shed any light on why this should be happening and what I can do about it?

Thanks,

Nick