If you upgraded from VirtualBox 4.3.20 to 4.3.22 and use Vbox network shares, you may have noticed shares are reported as unmounted, even if they are available.

This is a well known issue :

https://forums.virtualbox.org/viewtopic.php?f=2&t=66081 https://forums.virtualbox.org/viewtopic.php?f=1&t=66067#p312765

Solution for now is to revert to 4.3.20 (VB and extension) or wait for upcoming VirtualBox release