Cannot Delete

I am having a problem with the delete key in Word 2000 (and maybe excel, access, etc.) on a Windows 98 machine. For some reason, Office has decided that the delete key will no longer be used for deleting highlighted material. I can still place the cursor in front of a word and delete a character at a time, but if I highlight a whole word or more, the only way to delete it is with the backspace key. Any ideas?