You install operating systems from a bootable USB flash drive.

You frequently run diagnostic programs from a bootable USB flash drive.

However, you should leave USB flash drives at the top of the boot order if

You frequently use USB flash drives for other reasons.

You frequently use USB flash drives to shuttle information between computers.

You use USB flash drives to speed up your system using the Windows ReadyBoost feature.

We recommend changing the boot order on Windows 7 computers if However, you can also use your system’s DVD or BD (Blu-ray) drive for these tasks. More and more diagnostic programs can be run from bootable USB flash drives, and you can also install new operating systems from bootable USB flash drives. Should you change the boot order? It depends.

Change your BIOS or UEFI firmware settings to skip USB drives as bootable devices.

Don’t leave USB flash drives plugged into your system when you shut down the computer.

If your system restarts correctly, you have a couple of choices: Solution? Unplug the drive and restart your system. If your system is configured to use USB drives as the first bootable device and you leave a nonbootable USB flash drive plugged into your system (either directly or into a USB hub connected to your system), your system won’t boot. As always, start with the simplest possibility: You’ve left a USB thumb drive plugged into your computer.

Data or power cables from the internal hard disk to the motherboard are loose or have failed (hardware).

The computer’s system drive is not properly identified (BIOS/UEFI).

A nonbootable drive containing media is listed first in the boot order (BIOS/UEFI).

Possible reasons can include the following: These and similar messages indicate that the BIOS or UEFI firmware chip on the motherboard cannot locate startup files for your operating system. Typical error messages displayed by the BIOS include the following:

These messages might come from the system BIOS (ROM BIOS or UEFI firmware) or might be generated by Windows. When a system has problems starting, it might display error messages at startup. Learn More Buy BIOS Startup Error Messages and Solutions PC and Gadget Help Desk, The: A Do-It-Yourself Guide To Troubleshooting and Repairing

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