wpnonce problem

I’ve been using Duplicate Post in conjunction with the Menu Editor plugin to create a WP admin menu with one-click creation of new templated posts. I was baffled as it seemed that my settings were intermittently being ‘forgotten’.
I then found out that the url for ‘New Draft’ I’d copy from Duplicate Post and paste into the Menu Editor field would somehow ‘expire’ after a day or so – so clicking the link I’d get a “Are you sure you want to do this? Please try again.” Can’t find any mention of this anywhere – has anyone any ideas on a workaround? Thanks – S