stops you from individual competent to launch window, login, or start up the computer?
Answers:
Yes. Any exe infector to be precise poorly written and corrupts the kernel (win.com at window 98/me, ntoskrnl.exe at win2000/xp/vista) will impose the system to not boot.
There are virus that hurt Windows so that it does not operate correctly. That can produce the behavior you describe. Or your computer may be broken.