I had the same problem. I found a program that let me overcome this restriction. A-PDF Restrictions Remover from [url="http://www.a-pdf.com/security/restrictions_remover.htm"]A-PDF - Affordable PDF Tools[/url]
It comes with a 15 day free evaluation period, but after one test I bought it. Now in the right-click context menu for PDF files I have the options 'Remove Restrictions' and 'Remove Restrictions & Save as ...'.
Ethically I have no qualms. This is an information file that I need to process, and is sent to me directly from one of our customers. The security restrictions are a by-product of how they create and distribute the files - and provide absolutely no protection from prying eyes. A completely ficticious security.