XP Updates

[jimmygreen]

I appear to have the same or a similar problem to the two described earlier this week. I have looked at MS troubleshooter but the problem does not appear to be one shown there. I do not receive an error message.All that happens is that I receive a notice headed MS XP professional with front page. It then asks me to insert the CD rom which I do not have. I have tried to save to my hard disc and manually install but I still get the same message telling me the same update is ready.
So what is the problem and can any one tell me how to repair it or at least permanently cancel this particular update, or is that not possible.
Thanks