I got notifications saying to re-start Nautilus and so on for Dropbox to work, and of course lots of problems opening windows, tabs closing when they should come to the front, etc.
My solution was to remove Dropbox from the Start Up menu. But I still want to use it, of course.
My instruction from @heynnema for a solution was:
Using Synaptic, enter dropbox into the search area, and you should see dropbox, and nautilus-dropbox. Right-click on nautilus-dropbox and select Mark for complete removal. Left-click on dropbox and select Mark for installation.
Then go back to the search box and enter g15daemon, right-click and select Mark for re-installation.
Then click the APPLY icon. After it's done, exit Synaptic. Dropbox may ask you to restart Nautilus by clicking the OK button. Confirm that dropbox is working normally, as expected. See if your problem with Chrome/etc is resolved.
I opened Synaptic, but "normal" dropbox is not present, only php-dropbox, caja dropbox, thunar-dropbox-plugin, libnet-dropbox-api-per... and nautilus-dropbox, which I was able to remove.
(There are two other things installed: libg15render1 and libg15-1, both current versions.)
I searched for g15... and tried to re-install g15daemon and got the following message:
E: Internal Error, No file name for g15daemon:amd64
Then I tried remove it, and re-install and this did not work.
Then I removed it completely, and re-installed, which seemed to work, though I got a "package failure" notice and the message:
E: g15daemon: subprocess installed post-installation script returned error exit status 1
Finally, I closed Synaptic and opened Ubuntu Software, and tried to find Dropbox, but it was indicated that Nautilus-Dropbox was still installed. It could not remove it.