Here is a program that allows you to break the deadlock if your system is corrupt whereas you have important data on your hard disk.
xBoot is for creating a multiboot disk or USB key with one or more ISO images. It comes along with an interface that anyone can handle even without any computer knowledge. Nothing simpler; just drag and drop the downloaded ISO files into the interface and click to start creating the multiboot disk. It is possible to include any application or OS in the multiboot disk (Linux distribution, utility, antivirus, etc.).