Found out the other day that there seems to be an an issue with opening up PDF Files within external email programs (Microsoft Outlook Express, Microsoft Outlook 2003, 2007, 2010, Windows Live Mail, Eudora, Mozilla Thunderbird etc) and Adobe Reader X (10). When trying to open up a PDF using one of these external email clients or others, Adobe Reader X launches and gives the following error message:

There was an error opening this document. Access denied.

 Adobe Reader X: There was an error opening this document. Access denied.

At first I tried disabling “Enable Enhanced Security” under “Preferences > Security” but that didn’t work, after further investigation I found out that it’s to do with Adobe Reader X’s new Protected Sandbox Mode, the following fix/solution seems to work (at least for me):

  1. Open up Adobe Reader X
  2. On the Toolbar Menu go to Edit > Preferences
  3. Go to the general tab under Categories.
  4. Untick “Enable Protected Mode at Startup”
  5. If asked if sure, click Yes and then Ok.
  6. Now close Adobe Reader X and try opening the PDF again.

Hope that fixes the problem for others out there with the same problem!

For more information about this new “Protected Mode” Feature, check out the following links: