Need help with blue screen but not BSOD

Hello,

I work with serveral users and two of them recently reported blue screen. At first I though oh s&^#$ BSOD but no this one is the light blue screen that shows up when you’re about to get Windows login screen.

When the light blue screen shows up, they can only move the mouse ponter and there aren’t any icons.

Any suggestions what maybe the problem? (Windows 2000 sp4)

Thanks.