Stable version of Dropbox 1.6.3 has been released for Windows, Linux and Mac. This release is a minor update which fixes install failure in Windows 2000 and rare sync issue not working on Mac 10.4 and other small fixes were also offered with this release.
You can find Dropbox version you’re using by hovering your mouse pointer over Dropbox’s system tray icon. You can wait for installed Dropbox client on your Computer to upgrade to the latest version automatically or install new version 1.6.3 from below links.
Download Dropbox 1.6.3
Source: Dropbox forums