I dont think this is down to the security settings of the document, this is a very common problem tho and I have never yet really got to the bottom of the answer. Some of the answers on this site suggest to try Help – Repair Acrobat and see if that fixes it, or secondly, turn of Protected mode in the General Setting in Acrobats Preferences but after suggesting these, i have had no confirmation that they have fixed it. I have also supplied a couple of links that could be of use below.
Where is your document saved, is it on your hard drive or stored remotely.
Finally, what Operating System and version are you running as the mighty Xerox Phaser 7400 is the exact same printer that I have at the office which is an excellent printer. I am on a Mac running 10.6.
http://helpx.adobe.com/acrobat/kb/pri...
http://helpx.adobe.com/acrobat/kb/tro...