Hello, I had a heck of a time finding this and I wanted to post something in hopes that it will help someone else out: I recently had a customer with a problem where they could not open embedded Excel worksheets in a Powerpoint presentation. OS: Vista OFFICE: 2007 ALSO, I ran across the problem where double-clicking on a Excel link would not open the program. I found 2 places to check and then everything worked... 1) Excel 2) click on the office button in the top lefthand corner 3) go to the "Excel options" at the bottom of the menu 4) go to "advanced" and scroll down to "general" section. 5) Make sure that "ignore other applications that use Dynamic data exchange (DDE)" is unchecked. 1) Excel 2) click on the office button in the top lefthand corner 3) go to the "Excel options" at the bottom of the menu 4) go to "trust center" 5) go to "trust center settings" at bottom right 6) go to "add-ins" 5) Make sure that "require application add-ins to be signed by trusted publisher" is checked. Regards