For some Windows 8 versions Windows Defender will not let itself be "killed" by XXHighEnd and next treats XXHighEnd as malicious software (and logs you off when you press Play).
N.b.: As far as we know this is the case for all Windows 8.1 versions.
This is how to stop Windows Defender from being active :
Go to Start - Run - type gpedit.msc
Expand Administrative Templates (under Computer Configuration) and expand Windows Components :
Click Windows Defender :
and in the right hand side double click Turn off Windows Defender;
In there activate the "Enabled" radio button and click Apply :
Reboot is not necessary.
