virtualbox.org

I'm using Ubuntu as my host system and windows 7 as guest. Normally after screen of host is turned off (timeout) on wake Ubuntu shows login screen. However it changes if guest system (windows 7) is running and is focused when host screen turns off (timeout). Then on wake you are presented with guest system without any need to log in to host system. When guest system looses focus then host system goes to authentication failed and asks to login. Is there a way to make sure every time screen turns on host login screen is displayed?

That's something that you got to figure out between your host and your guest. I usually turn off all screen savers/locks and password protection from all of my guests, and the only thing I have to worry about is the host's screen saver/lock.

That, actually is the issue. I have turned off all screen saver/locks and passwords on my guest. So when host turns of screen after timeout while guest is in focus and wakes it doesn't require host password - it goes straight to guest without any passwords. Host password is requested only if I unfocus guest machine.

Then it's your host? That doesn't activate the screen saver? Maybe your host's display-power-saving kicks in before the screen saver?

On Guest (Windows 7) both screen saver and display turn off (In power settings) are disabled.
On Host (Ubuntu) there are following settings: Suspend when inactive is disabled, Turn off screen when inactive for 5 min and Lock screen when screen turns off is enabled.