Try making a new scene collection and adding just a game capture source, or get rid of the display capture source in your second scene. Display capture performs exceedingly poorly in Windows 7, even if it's in a different scene.
Run OBS as Admin and try enabling Aero
According to your log file Aero is disabled. The option in OBS will turn Aero off if it's enabled, but it won't turn Aero on if it's already off when OBS is launched. I don't think Aero would have an effect on anything but it's worth trying I guess.
http://ccm.net/faq/30281-how-to-enable-or-disable-aero-on-windows-7
Or switch to an Aero-enabled theme in Windows.
http://ccm.net/faq/30281-how-to-enable-or-disable-aero-on-windows-7
Or switch to an Aero-enabled theme in Windows.