Sleeeep

I get the weirdest problems. Another old computer (uses Win 98). This one works just fine at my house, but when I take it back to my friend's house it "goes to sleep." When I first plug it in it works fine, we run it through its paces, it works fine. Then I get a call. When she tries to turn it on, the monitor says "Sleep Mode in 5 seconds," and it goes to sleep and will not be awakened. I switched monitors, thinking it might be a problem with the energy saver in the monitor. I removed the screen saver from the computer... nothing seems to help. What the heck.
The only thing I can think of is that her house (I call it a house charitably) might have bad power... It has old, old wiring. Any thoughts?
Keith

 

ttt pls