Shared folder was earlier working for me but all f sudden it stopped working (Virualbox - host was Windows 7, Guest was OpenSuSe)
modprobe -a vboxguest vboxsf vboxvideo
then
mount -t vboxsf testsf /opt/tsf (testsf was the folder in Windows C drive which was added in Virtualbox shared folder --- and /opt/tsf is the folder in OpenSuse
