windows defender in my vista does not run at startup.i clearly sure it's not running at startup when there is no windows defender alert when i try to open fake "eicar.com" virus file (it's testing virus file which can be download at http://www.eicar.org/anti_virus_test_file.htm

However windows defender can detect it after i manually open windows defender.I already setup an option windows defender to always appear in notification area but it's still failed to start at windows startup.

help me
machinesof2029ad,there is no windows defender on the list? may that cause it's does not start at startup? how to list it?