I have the same issues. It started a couple of weeks ago when I couldn’t access my pdf files in the pdf viewer anymore. Even though that was annoying it was still manageable as I could still open the pdf’s in a separate pdf viewer. Recently Endnote started crashing often, easily up to 20+ times a day, mostly when I try to edit citations or import references. Very time consuming and frustrating issue to encounter when trying to finish a PhD.
Endnote Support was very friendly but unable to help me. I would hope they would have fixed the software issue by now. Any prospects of a solution to this problem?