It happens that centos6 may fail to get virtualbox running due to some kind of 'kernel-header' problem, in which the virtual box complains the kernel header does not match. The remidy to this is: 1. yum list gcc kernel-devel. Install these two if it is not. 2. Check the running kernel matches the kernel headers: uname -r #running kernel rpm -q kernel-devel # intstalled kernel headers 3. if the two versions do not match, run yum -y upgrade kernel kernel-devel reboot. My virtualbox in CENTOS6 then run successfully after the steps described above. Reference: http://www.thoughtpolice.co.uk/vmware/howto/centos-5-vmware-tools-install.html