This is not something that happens particularly often, but when it does, it can be extremely frustrating.
Every once in a while, I may be browsing the web, playing Doom, RollerCoaster Tycoon 3, or doing something else on my Windows 98 machine, and suddenly, the shell stops responding and everything becomes unusably slow. Most of the time, I can do the three-finger salute, kill every open application and Explorer, and the desktop respawns, and I can go back to what I was doing.
However, sometimes the system becomes so unresponsive that it completely locks up. The screen becomes a still image, the mouse pointer doesn't move, and the keyboard doesn't respond either. Even pressing the power button on the front of the case does nothing. Ctrl+Alt+Del has no effect, either. It's as if Windows was just frozen in time. I once let the machine sit for two hours like that to see if it would finish whatever it was doing, only to come back with it still locked up as ever. As much as I absolutely hate doing this, I have no choice but to hard reset. I hold the power button down for 5 seconds to forcibly power off the machine, and then turn it back on and wait for ScanDisk to take its sweet time checking the disk for errors before Windows boots up. This happens maybe once or twice a week for me, but it's still infuriating.
Has anyone else experienced things like this? Are there any ways to diagnose this when it happens and find the cause.