How to lock your computer using USB stick

sub key If you are tired of people who use your computer without your permission and change anything they like, here is a small trick which will not even allow your computer to boot without a USB stick , which acts as a key to boot your PC.

Understanding what you are going to do

When windows boots it checks for the primary boot device in bios which is by default is your hard drive.
Then it looks for a system file called as Boot.ini which tells windows where to start booting from. Without this file windows will throw you an error ” Invalid Boot.ini ” or “Windows could not start “

So what this trick does ? . It will make make the windows look for BOOT.INI in a USB drive Follow the steps

Make Hidden Files visible:

Boot.ini is hidden file by default. Open C drive and go to Tools > Options > View. Look for Hide Protected system files . Uncheck it. Now you should be able to see the BOOT.INI file.

Copy System Files:

Copy the files 1) BOOT.INI 2) NTDETECT 3) NTLDR to your USB stick. This is assuming that your windows is installed in C drive. In case its D drive look into D drive. Remove the USB stick

windows system files

Setting up BIOS

Now restart your computer and keep [ F8 ] key pressed as soon as the computer starts. After you get into the BIOS, Look for the menu item where you can change your Boot Device. After you find it, set USB device as first boot device and Hard disk as secondary .

Here what we have done is, when you computer starts it will first look for a USB stick to boot from. When it does not find it , it will look for your hard drive. Restart your system now.

Renaming Boot file

Now the main trick starts. Rename your boot.ini file as book.ini.bak. This way you have created a backup file which can be used in case you want to revert back.

Checking the setup

Now restart your system. Don’t insert your USB stick now. If you have done everything fine, you will be getting boot error. If not your BOOT.INI file is not renamed properly.

Using USB stick as key

Now insert your UB stick and reboot. You should be able to see windows loading properly.

That’s all. Now every time you need to load windows you will need to use your USB drive.

What if I loose my USB drive or it fails to work ?

You can make a Windows Recovery Disk or Follow the steps here to revert back. What it does is creates the boot.ini file again and your computer boots normally.

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About The Author of this article:
Ashish is one of the co-author of this blog and writes on various interesting softwares, PC tips and more. You can read more of his articles here.

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Tags: fix boot errors, lock computer, pc security, pc_tips, pc_tools

12 Comments and Link-Backs to “How to lock your computer using USB stick”

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12 Comments from Friends and Readers

Ravi, January 9, 2008:

Is there any other way of just modifying the boot.ini file. Since you have back it just renaming it should work
techsnack, January 9, 2008:

Great tips! but it is a but dangerous if we lost the USB disk. Although we can recover using the method above….
Ashish Mohta, January 9, 2008:

@Ravi: You have a point there. Infact I just forgot to mention it. If you can create a Start up disk you need not to follow all those steps.

Just boot with your start up disk ( Set Floppy Disk as first boot device or if you usb is there no change is required.) Then you can access C drive and rename boot.ini back.

Works like a charm
Jammy, January 9, 2008:

This is will be little risky. I dont want to loos access to my computer
Sahil, January 9, 2008:

I think it;s better to lock your computer with a password. With windows XP and up you can have user with password necessary. So why use a USB. Just make one account and enable password for it.
Ashish Mohta, January 9, 2008:

@Sahil: I agree with you on this completely. but I will tell you one situation.Many a times even if its locked people call you and ask for password and say I just want to use it. Its difficult in those times to say no.

With this people will just say “Damn the computer is not working”
katie, January 14, 2008:

Just wondering if this can be done on vista, as i can’t seem to find the option that’ll allow me to find those files, unless they have been renamed as there are some whicto do with the booting up, i think. Thanks
Ashish Mohta, January 14, 2008:

@Katie: Hi Thanks pointing that. I will try to find solution if possible and will answer in our weekly Readers Digest
katie, January 21, 2008:

thanks, that would be great
katie, January 21, 2008:

Thanks that would be great.
Justintas, July 17, 2008:

I’ve try on WinXP sp3 but my lippy still able to load OS even i have done the whole process well.
Just for your info. my lippy was equip with system mechanic software…. i not sure this related or not? this system mechanic was do backup the registry before.

ehhh, how to create startup disk, maybe i can try this.
michael, August 30, 2008:

how do you do this on vista? i saw a commnet referring to this but i couldnt find where you wrote the answer

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