'There are no PDFs attached to this reference' error message in X5 (Win 7)

When looking at a specific reference in my Endnote Library there is no connection to the pdf already present in my ‘EndNote Library.Data’ folder. There is a 'paperclip; icon present in the reference summary view but in the ‘PDF & Quick Edit’ view the erro message appears.This is a problem with several of my attachment, some show up as url icons although there is a pdf file present in the library.

Does anyone have ideas what I can do to correct this behavior? So far I have copied the .pdf file to the desktop and re-connected to the reference, this will correct the issue but there must be a better way?

Thanks in advance.