"happy" = lappy ???
Never saw a happy blue screen, they are SAD for most people.
But yes, laptop, or desktop. First option is to perform steps digitalzom-b stated
Should have looked at which forum, so ofcourse it's a laptop - dummy me.
Added: You can also put the Windows installation disk in and select repair and it will try to replair the OS. NOTE: if you did not get a Windows 7 Installation/repair disk, you can just borrow a copy to do a repair.