error message on start up

From: wendy (wendy_at_discussions.microsoft.com)
Date: 02/18/05 

Date: Fri, 18 Feb 2005 01:13:02 -0800

when i turn on my pc at the wall (windows xp) the on button is always on,
dont know if thats a problem but its just happening lately.
my main problem is when the start up screen comes up i get an error message
saying "bad check sum" i can either press f1 to continue or del to set up. i
havent a clue and im not a whiz with computers so i just press f1 and ignore
it. anyone know what this is please? thanks :) 

-- 
wendy