I have Dropbox installed on my Ubuntu machine, which is running Ubuntu 16.04, and it has worked fine until a few days ago, when I ran some upgrades through `sudo apt-get upgrade`, rebooted, and now Dropbox no longer starts.

If I run `dropbox start`, I get the following:

```
Starting Dropbox...dropbox: locating interpreter
dropbox: logging to /tmp/dropbox-antifreeze-gPhIu8
dropbox: initializing
dropbox: running python 2.7.11
dropbox: setting program path '/home/pascaltitle/.dropbox-dist/dropbox-lnx.x86_64-42.4.114/dropbox'
dropbox: setting home path '/home/pascaltitle/.dropbox-dist/dropbox-lnx.x86_64-42.4.114'
dropbox: setting python path '/home/pascaltitle/.dropbox-dist/dropbox-lnx.x86_64-42.4.114:/home/pascaltitle/.dropbox-dist/dropbox-lnx.x86_64-42.4.114/python-packages-27.zip'
dropbox: python initialized
dropbox: running dropbox
dropbox: setting args
dropbox: applying overrides
dropbox: running main script
dropbox: load fq extension '/home/pascaltitle/.dropbox-dist/dropbox-lnx.x86_64-42.4.114/cryptography.hazmat.bindings._constant_time.so'
dropbox: load fq extension '/home/pascaltitle/.dropbox-dist/dropbox-lnx.x86_64-42.4.114/cryptography.hazmat.bindings._openssl.so'
dropbox: load fq extension '/home/pascaltitle/.dropbox-dist/dropbox-lnx.x86_64-42.4.114/cryptography.hazmat.bindings._padding.so'
dropbox: load fq extension '/home/pascaltitle/.dropbox-dist/dropbox-lnx.x86_64-42.4.114/psutil._psutil_linux.so'
dropbox: load fq extension '/home/pascaltitle/.dropbox-dist/dropbox-lnx.x86_64-42.4.114/psutil._psutil_posix.so'
dropbox: load fq extension '/home/pascaltitle/.dropbox-dist/dropbox-lnx.x86_64-42.4.114/linuxffi.pthread._linuxffi_pthread.so'
dropbox: load fq extension '/home/pascaltitle/.dropbox-dist/dropbox-lnx.x86_64-42.4.114/tornado.speedups.so'
dropbox: load fq extension '/home/pascaltitle/.dropbox-dist/dropbox-lnx.x86_64-42.4.114/cpuid.compiled._cpuid.so'
dropbox: load fq extension '/home/pascaltitle/.dropbox-dist/dropbox-lnx.x86_64-42.4.114/linuxffi.resolv.compiled._linuxffi_resolv.so'
dropbox: load fq extension '/home/pascaltitle/.dropbox-dist/dropbox-lnx.x86_64-42.4.114/posixffi.libc._posixffi_libc.so'
dropbox: load fq extension '/home/pascaltitle/.dropbox-dist/dropbox-lnx.x86_64-42.4.114/librsyncffi.compiled._librsyncffi.so'
dropbox: load fq extension '/home/pascaltitle/.dropbox-dist/dropbox-lnx.x86_64-42.4.114/linuxffi.sys.compiled._linuxffi_sys.so'
dropbox: load fq extension '/home/pascaltitle/.dropbox-dist/dropbox-lnx.x86_64-42.4.114/PyQt5.QtWebKit.so'
dropbox: load fq extension '/home/pascaltitle/.dropbox-dist/dropbox-lnx.x86_64-42.4.114/PyQt5.QtCore.so'
dropbox: load fq extension '/home/pascaltitle/.dropbox-dist/dropbox-lnx.x86_64-42.4.114/PyQt5.QtNetwork.so'
dropbox: load fq extension '/home/pascaltitle/.dropbox-dist/dropbox-lnx.x86_64-42.4.114/PyQt5.QtGui.so'
dropbox: load fq extension '/home/pascaltitle/.dropbox-dist/dropbox-lnx.x86_64-42.4.114/PyQt5.QtWebKitWidgets.so'
dropbox: load fq extension '/home/pascaltitle/.dropbox-dist/dropbox-lnx.x86_64-42.4.114/PyQt5.QtWidgets.so'
dropbox: load fq extension '/home/pascaltitle/.dropbox-dist/dropbox-lnx.x86_64-42.4.114/PyQt5.QtPrintSupport.so'
Dropbox isn't running!
Done!

```

Furthermore, if I launch the Dropbox app, the icon appears in the dock, blinks a few times, and then disappears, with no apparent effect. If I remember right, when I first installed Dropbox, the icon would blink, and a Dropbox login page would load via Google Chrome. But that is not happening now. I can open Chrome and log in to Dropbox via the web, no problem.

Following advice below, I tried installing `nautilus-dropbox` with aptitude, and I get the following output:

```
sudo aptitude install nautilus-dropbox
The following NEW packages will be installed:
  nautilus-dropbox 
0 packages upgraded, 1 newly installed, 0 to remove and 0 not upgraded.
Need to get 2,720 B of archives. After unpacking 45.1 kB will be used.
The following packages have unmet dependencies:
 dropbox : Breaks: nautilus-dropbox but 2015.10.28 is to be installed.
The following actions will resolve these dependencies:

     Keep the following packages at their current version:
1)     nautilus-dropbox [Not Installed]    

Accept this solution? [Y/n/q/?] Y
No packages will be installed, upgraded, or removed.
0 packages upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
Need to get 0 B of archives. After unpacking 0 B will be used.

```

This seems to indicate that I have some missing or broken dependency, but I'm unclear on how to proceed. 

Any suggestions?