I am having the same issue, I have and old mac book pro laptop that I use Evernote on & I recently got a new mac book pro and put Evernote on it. I am guessing it is a conflict between the two instances of Evernote & the two machines. I am running v 10.4.4 and am experiencing some slowness and I am having a problem where I add new information into the note and when it syncs that info will disappear. I am guessing I will go back to google docs until Evernote works out the bugs :(