PROBLEM WITH Word for Mac 2011 and EndNote X5

EndNote has been working well for me until today.  I have it installed on my iMac and my Macbook Air.  I keep my library synced on both computers using Dropbox.  

Today, on both computers when I try to open EndNote, I get the logo box for a couple seconds, then it goes away and nothing opens.  If I click on the specific library to open, it gives me a box with the error icon (triangle with exclamation point) and says "the document “My Library.enl” could not be opened.  

HELP!!

OK - so, I found the answer… tools → recover library

it worked.  thank God!! 

Unless something has changed, I would not use a library in the drop-box, and only put a compressed version there and move it to the hard-dirve before openning and using.