I am having the exact same issue as in this question but none of the answers worked for me.
For instance, trying this answer I get this error:
a@b:~$ cd /usr/bin a@b:/usr/bin$ sudo cp dropbox dropbox1 [sudo] password for a: cp: cannot stat `dropbox': No such file or directory a@b:/usr/bin$
Is there a way to fix this?
Reinstalling and selecting "Start Dropbox on System Startup" worked as in