Thanks to Sarah who first spotted the problem and Debbie who found a quick fix:
We have verified with ScienceDirect that there is a small glitch with downloading/saving ScienceDirect PDF files and Adobe Reader X (10). Adobe Reader X experiences a glitch when you open the article directly from ScienceDirect into Adobe Reader, with a LEFT CLICK of your mouse. This sometimes renders the Adobe Reader X toolbar nonfunctional, so you cannot use the icons to download, save or print the article. Please use this workaround instead and bypass the Adobe Reader X frame.
Using your mouse — RIGHT CLICK the PDF file link……this will open a drop down menu that will have the option to ‘Save Link As’ or ‘Save Target As’ depending on which browser you are using. This will then prompt you to save the article to a common file on your hard drive. After you click ‘Save’ from the window that opens, you can then go back to the file and open the PDF you have saved.