if you pick f12 for start up, it will take you into boot menu" in there pick (safe mode) with the up and down arrows on the keyboard, and press enter,, it will now start in (safe mode) when it starts up as windows, go to the start in the bottom task bar, cilck on it, go to (all programs)( ACCESSORIES) (system tools) (system restore) click on system restore, it will take you to a calander, pick a date back in time when you rember when your pc was working as normal. 3 weeks ago. lclick on that date , and NEXT ,and it will bring the setting change back to the way it was , and it should start as normal, ps googel (SYSTEM RESTORE FOR XP, for more info..
m, April 2011