Type XP NUMLOCK BOOT OPTION into google.com to find out how to set XP to set this at boot but most of the time this happens when you install a keyboard driver or enhancer. Fix? Don't use such or ask the keyboard maker for a fixed driver.
After a reformat and installation of XP_SP2 I have the same problem on two new keyboards. A new bog standard UK keyboard with the number keypad on the right
= "Standard 101/102-Key or Microsoft Natural PS/2 Keyboard", and another new usb wireless keyboard of similar layout, = "Logitech HID-Compliant Keyboard". The NUM Lock key is on at boot up but the number keys will not work. If I take the NUM key off the alternative keys do work! I have tried setting XP to 'English keyboard' and 'English extended keyboard" neither make any difference. I feel some system file is missing on boot up. Help would be welcome to solve this annoying problem.