W2K Bootup

I have 2 HP computers and 1 DEll that are all running W2K Professional and all 3 get to the “starting” Windows point where you can press F8 for troubleshooting and they ALL stop booting up and sit at that screen for hours. I’ve reloaded the operating system, reformatted and even changed out the memory. No luck!! Does anyone have any ideas of what can be wrong?