Using 1.5.5f currently.

When in Categories/Products, and updating a product ... when I press Preview I get the "Forbidden - don't have permission to access this resource message."

This just started happening suddenly, as I just updated this same product only a couple of days ago.

Can't update any existing product under any category (at least any I tried), but I can create a new product and update it.

What could be causing this?