U must try opening on different system
Try copy & paste on different location on ur system eg. C: drive or my document.
check the attributes , hope its not on 'Read only'.
Are all PDF files on that CD giving PROBLEM?
-> You can use the PDF OPTIMIZER to change the pdf to that of an earlier version to see if the problem goes away.
?see more: http://community.office365.com/en-us/f/172/t/281213.aspx