Ubuntu freezes completely including mouse, keyboard

I recently downloaded Ubuntu Linux on my laptop as dual boot. Ubuntu was freezing everytime after login ( it can work for a max of 3 mins before freezing). It completely freezes including keyboard, mouse and only solution is to force the computer to shut down. The problem resolved itself on its own. Unfortunately because I allocated too little disk space for Linux I had to uninstall and reinstall it. I tried doing system update but I cannot reach that point before the computer freezes. It is now freezing again and I'm in a hurry I need to work on it today! Is there anything I could do?