In short, if you use Dropbox, Google Drive or Sharepoint or another syncing program, that is likely the problem.
A. Move your EndNote database folder away from Dropbox and Google Drive, and back up your data using Endnote Web syncing.
OR
B. Right click on the Dropbox (great) or Google Drive (evil) or Sharepoint (not as evil, Office 365 rocks!) icons and pause syncing while using EndNote.
More details and a digression:
Jason from Endnote Tech Support explained that the similar problem I have been reporting ever since Endnote 5 (perhaps even 4) is likely related to my using Dropbox and/or Google Drive. He explained that when you work in Endnote, there are updates made to the various MySQL databases found in the RDB folders with the DATA folder that is created with an identical name to your endnote *.enl file. These databases end with *.myd or *.myi extensions.
Even if you don’t have PDF attachments to your records, the various indexes and such are stored there in the /*.DATA/RDB folder. What happens is that when Dropbox or Google Drive or any other syncing program (such as the www.secondcopy.com program which I highly recommend for periodic backups to removalbe media) syncs the changes on the hard drive to the Dropbox or Google Docs in the Cloud, Endnote may also be simultaneously trying to make a change that requires updating the MySQL file. This can and does reliably corrupt those files. So it’s note really your “database” that is corrupt; no need to have a hard attack!
Anyway, for a couple of years now this would happen constantly, and the only explantion I would receive was that I shouldn’t open the databases by clicking on them; use File/Open instead I was told about a year ago. But it kept happening. Apparently, however, Endnote figured out just about a year ago what was happening with Dropbox reported that this was happening with MySQL databases in many applications, not just EndNote. The solution(s) are simple:
A. Move your EndNote database folder away from Dropbox and Google Drive, and back up your data using Endnote Web syncing.
OR
B. Right click on the Dropbox (great) or Google Drive (evil) or Sharepoint (not as evil, Office 365 rocks!) icons and pause syncing while using EndNote.
P.s. Did I mention Google was evil? Google Drive will permit pausing, but once you have paused it will no longer respond to right clicking! I mean, why expect Google to produce a useable application, they rule the universe, why bother with users. So you end up having to Control/Alf/Delete and stop the process and who knows when it will start again; most likely next time I re-boot. Google is evil because for instance it first allowed you to have Google Docs but then practically forces you to download it’s substandard application; it wants to own your hard drive you see.