Professor Ronald Mallett thinks he can build a time machine this century using light. Information from the future could be sent back to when the machine is turned on.

What happens if in the future you don't sent back the information that you received when you turned the machine on from the future?

So say I switch on the machine and a message saying "Hello from 2009!" appears but when we get to 2009 we don't send that particular message back. This is some kind of paradox or is there a simple answer?