Endnote X2: Attached PDF's Won't Open

I get the following error message when I double-click the PDF icon attached to a reference:

“This URL (\L:National Louis University\Endnote\Chapter 2\CCL Chapter 2.Data\PDF\Angelica - Resolving conflict-0766532112\Angelica - Resolving conflict.pdf) could not be launched.”

I get a similar message regardless of the specific PDF or reference.

Any suggestions?!?