1. Enable the USB Controller and USB 2.0 (EHCI) Controller from the Settings menu.
2. Logon to the virtual machine, plug in the flash drive to the system then right click on the USB devices logo at the buttum of the window and select the flash drive just lugged in.
3. After a few seconds, a new file folder started up at the Desktop. The flash drive can be used from now.
4. Folloing is the list of mount point for the flash drive on popular OS.
CentOS - /dev/sda1
OpenSolaris - /media
Ubuntu - /media
Solaris 10 - /rmdisk
5. The flash drive should be mounted and unmounted like a normal disk.