After migrating a user's profile and changing ownership on their home folder the user was unable to log into Dropbox after logging in. The users received an error:
"Dropbox needs to change permissions for the Folder: ~/Users/.dropbox Type in your password to allow this."
Typing in the user name and password did nothing. The user was then presented with another window that said, "Couldn't start Dropbox. This is usually because of a permissions error. Storing your home folder on a network share can also cause an error."
The solution that worked for us was to remove the hidden "./dropbox" folder from the root of the user's home folder. You can do this from terminal by typing:
sudo mv ~/.dropbox ~/.Trash
Or you can do it from the GUI if you turn off hidden folders.
I have also heard that you should delete the DropboxHelperTools folder although that wasn't required in our situation.
sudo mv ~/DropboxHelperTools ~/.Trash