Comment 4 for bug 653133

OK, thats what I thought, I was just confused because I do not have a "Files" entry in my "Places" folder.

These are the things you can please check:

In your homefolder in the file .gtk-bookmarks is a list of the entries of the "Places" folder. They should be names something like:
file:///home/yourname/Documents
etc.

Then you can check if the file ~/.local/share/applications/default.list exists and if there are any entries. (Does not exist per default)

Then check /usr/share/applications/defaults.list and in particular the entries for:
x-directory/normal=nautilus-folder-handler.desktop
and
inode/directory=nautilus-folder-handler.desktop

What kind of 10.10 are you running? Could it be a misconfigured development build?