# Windows XP & Win 7 dual boot
Control panel, system & security,admin tools, system configuration,BOOT set as default
# Boot failure
Use boot media, next, repair your computer,troubleshoot,advance option,command prompt,
bootrec /fixmbr, bootrec /fixboot, bootrec /scanos, bootrec /rebuildbcd, All, X, continue

Win XP boot fix
https://kb.wisc.edu/helpdesk/page.php?id=5836
https://answers.microsoft.com/en-us/windows/forum/all/stop-0x0000007b-blue-screen-error-on-windows-xp/05fed568-ac69-4a64-addd-912ab6ac73a4

Transfer your Operating System from a CD/DVD to a Bootable USB https://www.dell.com/support/kbdoc/zh-tw/000132449/how-to-transfer-your-operating-system-from-a-cd-dvd-to-a-bootable-usb?lang=en

How to Copy a Bootable CD to USB https://www.techwalla.com/articles/how-to-copy-a-bootable-cd-to-usb