I then noticed that the Dropbox icon was missing from Menu Bar at the top of my desktop. I tried several things including uninstalling and reinstalling but nothing worked. After a little Google searching I found this:
1. Start a Terminal Window
2. Type the following into the Terminal Window and hit ENTER:
sudo rm -rf /var/lib/dropbox/.dropbox-dist
3. Type the following into the Terminal Window and hit ENTER:
dropbox start -i
4. If asked for your sudo password (mine did) type it in.
5. Wait a few seconds and you will see in the Terminal Window that it is downloading the Dropbox program and then unpacking it.
6. After step 5 finishes your Dropbox should be working again and you should see it's icon is back in the Menu Bar.
