Hi I solved my problem with this procedure:
1) I change all my stuff on Dropbox to a new folder. In my case, I named it Off Dropbox.
2) At www.dropbox.com I deleted all my stuff. It´s not so simple, It takes several delete actions.
3) In my Mac, I uninstalled my Dropbox following this link: https://www.dropbox.com/help/41
4) I deleted App in the Applications Folder and restarted my Mac.
5) I Downloaded the new dropbox app from dropbox.com and Installed it on my Mac again, using the default location.
6) Then I put back some files, when the syn was finished, I put then all my files back to the Dropbox folder.
It´s works fine for me.
Best regards
Yours
Rodrigo.