Vista - How do I start Windows Defender ?

I have just got myself a new computer and everything is working fine, except I cannot get Windows Defender to open. No matter what I try I get a message saying that the service has been prevented from starting and that I should start it manually. Can someone out there please tell me how I might do this? Many thanks in advance as usual !!

Open up the control panel then go into Administrative Tools then open up the Services then scroll down to Windows Defender then right click on it and go into the properties then for the startup type it should be on automatic delayed then ok everything. After that right click on windows defender and select start then you can open windows defender.

Thank you so much ; that did the trick. I wasn't able to set it to "Automatic Delayed", it said the parameters were not correct but I set it to Automatic, rebooted and it worked just fine. Thank you so much. Now, how do I click on the balance thingy to say thank you ?!

See where the red triangle is right next to it is where you need to click on.

Or leave it alone - Im guessing Mcafee turned it off while installing and regard Windows Defender as an incompatible 3rd party application. Like Norton does. They wont recommend you to enable. Check Mcafee Support.

I think that you're right because I had an error message from McAfee saying that I wasn't fully protected and it automatically fixed things! I also had Comodo Boclean running so maybe I was being too enthusiastic. I have now disabled WD.Thank you for your help.