Navigate the the location below in your registry and make the corresponding change.

This section can also be modified for each user by changing the same value located at:

[HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Winlogon] 

Please note that if you make changes to both "Current_User" and "Local_Machine", "Current_User" will be the one that is used by the system.

Key:[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon]
Value Name: RunLogonScriptSync
Data Type: REG_DWORD
Data:(0 = disabled, 1 = enabled)