Help! XP freezing at welcome (profile select) screen. Xpost from r/techsupport

My parents' outdated Dell desktop is freezing at the screen where you select which XP profile you want to use. The computer starts up fine until this screen, at which the mouse is unresponsive. I tried using MouseKeys, but LAlt+LShift+Numlock doesn't enable it. I can't seem to find any keyboard response either, but I'm not entirely sure this screen enables this anyway. I've tried multiple mice, and none work. Any help is appreciated.