TKKB0001.1.1 You have to reinstall Windows. In this case You need to format C Drive. C Drive you cannot format whilst inside Windows OS. Things to do before formatting C Drive. Copy desktop items and say place in folder fldrDesktop in another drive F. Copy My documents in a folder called fldrDocs_(your name). Copy all

After Restarting BIOS Press F10 key  or ESC key(for HP Computers). Enter BIOS Settings.  Move cursor to BOOT menu. But you have to use keyboard arrow keys. (lower right).  There are four choices . Pick Removable Devices. Save by pressing "Save Changes". NOTE! Place your removable USB or hard disk and attach to pace before