This is a good soft to run several OS at once , but there are many problems occuring after the installation of VirtualBox . 1)Any USB will be not detected. 2)For laptops the network adapter will not work. 3)For windows , the machine will never get shutdown untill you plug out . So the virtual box developers are not able to provide solutions for this. (Note: This error is possible specially for HP compaq 6710b Windows 7 Ultimate 32 bit users ) As a solution VMware is better for virtual machine , but the file size of vmware is bigger to download. How ever it gives 0 problems for many users , rather than virtual Box )