A Windows XP-based computer does not start after you unsuccessfully try to upgrade to Windows Vista

When you try to start a Microsoft Windows XP-based computer after an unsuccessful upgrade to Windows Vista, the computer does not start. Instead, a black screen appears together with a blinking underscore.

You may experience this issue if the computer uses a third-party boot manager program such as PowerQuest BootMagic or GRand Unified Bootloader (GRUB).

This issue occurs because the Windows Vista Setup program does not restore the third-party boot manager program.

To work around this issue, use the Windows XP Recovery Console to write a new boot sector to the system partition. To do this, follow these steps:

1. Use the Windows XP CD to start the computer.
2. At the Welcome to Setup screen, press R to repair Windows.
3. Log on to the Windows XP installation that you want to repair.
4. Type fixboot, and then press ENTER.
5. Type y, and then press ENTER to confirm that you want to write a new boot sector to the system partition. When you do this, the following information appears:
   The new bootsector was successfully written.
6. Type exit, and then press ENTER to exit the Recovery Console.
7. Restart the computer, and then finish the Windows Vista upgrade operation.
8. Reinstall the third-party boot manager program.

The third-party products that this article discusses are manufactured by companies that are independent of Microsoft. Microsoft makes no warranty, implied or otherwise, regarding the performance or reliability of these products.