Backspace peculiarities in Word 2002

Hi All

I have a problem within Word 2002, when I click on the backspace button instead of it deleting one character to the left it jumps back to the beginning of the entire word. very frustrating, I have trawled through the options to see if I can resolve the problem by un-checking anything obvious but to no avail. Any help would be greatly appreciated.

I’m running Windows XP PRO on a Dell latitude D400.

Thanks in advance