All I want to ask is this. Yesterday, I managed to install Windows 7 on a portable hard drive. So the problem here is that, I want to try to open the windows in the hard drive of another computer. But it cannot open the windows when it was in its boot through a portable hard drive. Â However, it can be opened if it's in my computer.
What is the solution?
What i have understood from your question is that,  you copied windows 7 into a portable hard drive but the problem is it does not run at boot or simply it's not bootable. I will tell you how to create a bootable disk, just follow my instructions:
1. Format the USB as NTFS. After that, go to My Computer and right click the drive name->properties. In the format box, select NTFS and click start.(image 1).
2. Now, go to start->run type cmd and press CTRL+SHIFT+ENTER.
3. In command prompt, type disk part. Wait for some time and then type list volume and press enter.
4 Find the volume of your removable drive.
5. Type select volume, Â * where * is your volume number. and press enter.
6. Now, Â type active and press enter, then type exit and press enter.
7. Now, create a boot sector for this, first find your DVD drive or in your case, the path to download windows 7.
8. For example, Â its drive f. In cmd, type f and press enter. Â Next, type boot sect(space)/nt 60(space), flash drive name and press enter.
That's it! you now have a bootable pen drive.
Awesome! Now,  I can create a bootable disk! Your new useful advice means so much to me.
Seamus thanks.
The reason why you cannot boot the other computer from your bootable external hard drive is because the hardware registered to the operating system is from your computer. You cannot run any version of Microsoft Windows if the computer you used to install the operating system is a different computer. You can only run and use the Microsoft Windows operating system on the computer where you install it.
This is also the reason why you cannot boot another computer using your own machine’s system drive. The drivers and hardware settings registered with the operating system will not match the ones on the other computer. Even if you managed to create or install Microsoft Windows on an external hard drive, you will still not be able to use it to boot other computers.
It is strictly for your computer use only. If your local or internal hard drive where Microsoft Windows is installed gets damaged or unable to boot, you can use your bootable external hard drive to boot your machine and then you can do the repairs.
