Hi, I've a Dell Optiplex 390 with Win10 installed. Yesterday I added a new HDD and I installed WinXP on to it. Now Windows XP boot fine, but if I try to boot from the Win10 HDD, it fails and instead boots WinXP HDD. I've tried to repair the Windows 10 through a Win10 Installation USB key, both automatic repair and bootrec commands, but seems that it doesn't find any Windows installation. How can I do?
I can't see any BOOT.INI in any HDD (yes, also in hidden files). EDIT: I found it; I should delete it?
If you removed Windows 10 HDD before installing Win XP, the boot loader on Win10 HDD should be OK and you need to enter BIOS/EFI setup utility (usually F2 or Esc key) and change the boot order (to first boot Windows Bootloader, aka Win 10). If you installed WinXP on to a second HDD while Win10 HDD was still connected to the machine, Windows XP installation destroyed boot loader for Windows 10. In this case boot loader for Win10 can be repaired by executing commands like: bootsect {/help|/nt60|/nt52} {SYS|ALL|<DriveLetter>:} [/force] [/mbr] Example if your Windows 10 partition is C: bootsect /nt60 C: /force /mbr If your Win10 HDD was formatted in GPT and your computer uses EFI instead of BIOS, the boot-loader should still be there on the disk without any damage. Enter EFI setup and choose "Windows Bootloader" for boot device (to first boot from). PS: For bootsect command you will need bootable Windows 10 medium (DVD or USB), also before executing command blindly, check that Windows 10 is C: volume, if it's D, E or any other drive letter, change the bootsect command appropriately. If you still have problems booting afterwards, post image of your partition layout (from some HDD partitioning software, of both HDD's) and picture of your BIOS/EFI boot selection screens. Edit1: Here is a good article how to repair dual boot system, just see Windows 10 section: https :// neosmart.net/wiki/repair-dual-boot-configuration/
Now that you have your Win10 working again, you should NOT re-install WinXP (if you haven't killed the XP partition already). You can only add boot entry to Win10 BCD via BCDedit command. After adding boot entry to BCD when computer starts it will ask you to select which OS to load... You can even specify the default OS and after how many seconds system should boot to default OS. Here are commands (example, haven't tried them myself, so be carefull, make backup of BCD first): bcdedit /create {ntldr} /d "Windows XP" again you need to know what drive letter is for Win XP partition bcdedit /set {ntldr} device partition=E: bcdedit /set {ntldr} path \ntldr bcdedit /displayorder {ntldr} /addlast To backup BCD: bcdedit /export X:\BcdBackup\LastBackup To restore BCD: bcdedit /import X:\BcdBackup\LastBackup refs: https :// docs.microsoft.com/en-us/windows-hardware/drivers/devtest/adding-boot-entries https :// docs.microsoft.com/en-us/windows-hardware/drivers/devtest/changing-boot-parameters https :// docs.microsoft.com/en-us/windows-hardware/drivers/devtest/changing-the-default-boot-entry https :// docs.microsoft.com/en-us/windows-hardware/drivers/devtest/changing-the-boot-menu-time-out