Dropbox is ending support for OS X 10.5
 

Its notifying users a couple of months beforehand. There are still a lot of users out there running older builds of Mac. One of the biggest reason for this is hardware incompatibility. Some older Mac machines are not compatible with the more recent builds of the desktop software so that’s as far as users can...

http://vr-zone.com/articles/dropbox-...0-5/85918.html