Can not open Windows Defender

[lyndhurst]

 Vista Home Premium
 Windows Defender is turned off. clicking on "Turn on and open Windows Defender"
 the message is Error oX80070564

  Trying to see which programs are running when windows starts.

[Geek-9pm]

Your question was considered elsewhere a few years back.
http://answers.microsoft.com/en-us/protect/forum/protect_defender-protect_start/0x800705b4-window-defender-error-code/39cfc886-bbec-4b48-9503-5a6c59bd1694

Does that work for you? 

[lyndhurst]

It did not work because I probably could not follow the directions properly. It starts with "Open Run"
      Do I click on "Start" and type ln  "Services, msn" in search window?

 Note for Step 1.  Fire Wall is on and I have Norton by Symantec but it was never activated.

[patio]

Thats part of the issue...you should only have 1 A/V app installed...Defender and Norton are both A/V apps....decide on 1 and ditch the other.