Which desktop did you chose -- KDE or Xfce?
Logging in to the desktop as root is a security risk. Better to create an ordinary user and log in to the desktop as that user. That might fix the problem, too.
To add an ordinary user (assuming you have installed VirtualBox Guest Additions)
/usr/sbin/useradd -c Skelley -d /home/skelley -g users -G audio,cdrom,netdev,plugdev,power,scanner,vboxusers,video,wheel -m -s /bin/bash -u 1000 skelley