Installing Windows and it keeps on looping

I started to install windows and someone messed with it half way.
So I started again.
Now when I install it it does the set up, get to 100% restarts and then takes me back to the beginning where I have to choose my country and choose install etc.

There is nothing wrong with the USB I'm using because I've installed several other computers with it (I work at a school).

This computer was sent away to be fixed (new hard drive). Could there be something wrong with it? Or should I install a different OS and clear the hard drive then install Windows again?

Any advice would be appreciated as this hasn't happened before and I've installed Windows 7 successfully hundreds of times.

Thanks

Hello and welcome to the forum.
This is going to sound stupid, but since it just happened to me the other day when installing Windows 8 RTM from an attached USB HDD.
After the install completes and before the computer boots to the first run setup / final stage of the install process...... Do whatever you need to do to get back into the BIOS and check your default disk boot order.
Sometimes and I assume on some boards with some BIOS utilities, when you evoke the Boot Option menu during POST by tapping the F12, F11 or whatever key more than one time it will actually reset the default boot order in your BIOS to the Boot Device you have chosen from the Boot Menu, don't ask me why but it has happened to me more than once.
Hope this helps
Regards
Randy

It may help to remove the install media during the first reboot..

@Both previous answers: usually the temporary change of boot device works fine, and after reboot it goes to the primary boot, but sometimes it hangs. I had these problems mainly with Windows 98, where I had to be fast as a lightning to get the CD out before it started to re-install... well, increased heartbeat is healthy, now and then. Cheerio.

You can get a lot of help from this blog.. though you all the guys have shared interesting and useful tips. if you need any help you can go through this blogInstall windows 7 on Mac

Hi,
Thank you so much. Went into BIOS and changed the boot settings and it worked.
I'll know what to do if it happens again - very strange that I have 20 of the same computers and only 1 had this issue!

CMOS battery? Has the computer been standing a longer time? You might want to check the battery, because if it is the reason for failure, it will break down again. Cost = negligible.

Thanks, if it happens again I'll check on that. I have replaced batteries in computers before so I'll manage that one fine! :-)