Kill large numbers of stuck workflows?

Hi,

I have an unfortunate situation whereby an old version of a workflow has become 'stuck' because it entered a state with no matching transition out of it.

In the meantime, someone else added in some 800 records for testing, all of which have now become 'stuck'. Is there any way to batch cancel such workflows, as unfortunately it stops new instances of the workflow from running?

As a workaround to the running issue, I suppose I could duplicate and rename the workflow so that NS sees it as a different workflow, which would then execute. However, it's still not great having old workflows stuck on a record (even though the end users won't ever see them, only admins get to see the active workflow/history tabs) and I do not relish stopping ~800 workflows by hand!