Problems reinstalling OS

[Whirlwind990]

So im currently repairing a friends laptop, because when it gets to the windows 7 start screen (just before it loads the desktop) the laptop reboots for some reason and just keeps going this cycle of boot, reach end of boot/prepare desktop, reboot (etc). Ive decided to reinstall the OS... So ive got an old copy of XP to test that but whenever i go to the system tools to install the OS it does not pick up the internal hardive... So I tried to connect and install the os on an external HD (which it did fine) but when it boots I dont know how to get it to boot from the external HD (and thus XP) and not the faulty windows 7 boot instead. Any ideas?

 

[Dragonraihan]

You didn't mention witch model the laptop is
Try to reconnect internal HDD if its not work let me know

 

[Prostar Computer]

Why are you testing with XP?

You should be able to select the external HDD in the boot options in BIOS or use the quick boot menu. If you're unable to select it in either of those, the BIOS does not support it.

 

[Whirlwind990]

Its a Toshiba
Because i only have a copy of XP and friend lost the discs for Windows 7.... Reconnecting internal HD did not work.

Ill try and boot from the BIOS and see how that goes.

 

[Prostar Computer]

Can you get into Safe Mode on the Windows 7 drive (I doubt it, but it's worth a shot)? There's this guide, but you will need either the repair disc or Windows 7 install disc: http://www.tomshardware.com/news/win7-windows-7-mbr,10036.html