All my files started re-syncing and the app is still 'indexing'

Sorry to hear about this, ESanders.

There's really no way to determine what might cause your files to re-sync; it could have been a third party app looking at your files, like an antivirus, for example.

Is the indexing process stuck? Usually indexing takes much less than actual syncing, so you should be good soon.

If not, please hover your mouse over your Dropbox icon and let me know the current sync status and version of the app.

Thanks in advance.