gistfile1.txt

http://crunchbang.org/forums/viewtopic.php?pid=414074#p414074

This happens because nvidia driver overrode OpenGL library (libGL.so). This workaround works for me on kubuntu 14.04.
1) close dropbox session
2) find your nvidia system folder: in my systems it's /usr/lib/nvidia-304 (if you using another version of nvidia driver, for instance nvidia-331, your directory should be /usr/lib/nvidia-331
3) find dropbox system library: in my system it's /var/lib/dropbox/.dropbox-dist/dropbox-lnx.x86_64-3.0.5/
4) backup your's dropbox OpenGL library: #mv libGL.so.1 libGL.so.1_backup
5) make symbolic link to nvidia's OpenGL library: #ln -sf /usr/lib/nvidia-304/libGL.so.304.125 /var/lib/dropbox/.dropbox-dist/dropbox-lnx.x86_64-3.0.5/libGL.so.1
6) start up dropbox