# Ribbon disappears randomly and cannot open site in SP Designer

We've been running our SharePoint site (public facing, publishing with workflow site) for a few months, but recently we've found that randomly the editing ribbon will disappears for all users who are meant to see it. I've tried things like IISRESET to fix it, but nothing seems to work except time, i.e. if we wait a while it'll just reappear and everything works well again.

As this is a public facing site for customers and prospects, I've used security trimming in the master page to only show the ribbon for authenticated users with ManageWeb and AddAndCustomizePages permissions. Therefore, only my colleagues and I should see the ribbon when we log into the site.

When the ribbon does disappear, I've also found that I cannot open my site using SharePoint Designer - I forget the exact error message, but I'm pretty sure it said I didn't have permission to open the site.

I know this is a very brief description of the problem, and I will update this question when the ribbon next disappears, to provide more info (and exact error messages for SPD), but I'm wondering if anyone has ever seen this odd behavior before, and knows how to resolve it?

Kevin