Dropbox suddenly doing a complete reindex?

Hey there PHR -  thanks for lettings us know about this. 

I'm sorry I don't have a better answer for this one, but things like beta versions and symlinks are usually the culprits for such behaviors.  As beta builds are still in the testing process, you could experience some issues or an inconsistent experience. When symlinks come to play as well, all hells can break loose. 

Symlinks may reference locations where Dropbox (i.e. our client) may have limited accessibility and can cause various issues. High CPU usage, poor syncing performance, permissions issues and quota usage disparities are a few of the problems that often come up when symlinks are added to the Dropbox folder.

As a first step to isolate the issue, I'd highly recommend that you install our latest stable version of the client. 

To do this, you will first need to follow these steps to verify that you have opted out of "Include me in early releases" option in your settings on Dropbox.com. This will ensure that the application does not automatically update to the beta build after you install the latest stable build:

1. Log in to www.Dropbox.com using your web browser.
2. Click on you account picture/avatar at the top right corner of the page.
3. Click on "Settings".
4. From the "General" tab, scroll down to the section titled "Preferences" and uncheck the box next to "Include me in early releases" if it is checked.

Then, use the following link to install the latest stable version of the Dropbox desktop application:  https://www.dropbox.com/downloading?build=70.4.93&plat=win&type=full

Once you install the stable build, it might take some time to re-index the files and sync any pending changes.

Please let me know the results!

PS: Instructions on how to remove symlinks if needed, can be found in the following Help Center article: https://help.dropbox.com/desktop-web/high-cpu-usage