It had been a while since I used my windows defender. Last night I went to use it and it was not there. When I click on it I am told " file not found ".I have tried to access it through the control panel as wellas programs. It is like it was never on my computer. I also tried to download windows defender from windows down load and I got a message that read " windows vista came with windows defender" the down load was not completed.What I would like to know is, what could have possibly happened and how can I get my windows defender back. Oh yes, I also went through my msconfig. then start up. It does list defender but it says 0% program file. I am not sure what else to say, that is pretty much my problem. Thank you for everyones time.