I'm running Windows 8 there, but my official not beta version is 7 Pro.
The only think I can think of that would cause Windows to lose it's genuine certificate regularly would be that you're running a pirated copy, and forgot to turn Windows Update off. Otherwise, it happening once? Possible. Twice? A little more out there, but some people are that unlucky.. It happening to you, your brother, and all your computers at school over and over again? That just flat out doesn't happen.
No offense, man. Maybe you're computer jinxed, and are honestly experiencing all these problems. Besides that, the only reasons I can think of that explains your situation (besides the two "open" commands, which is weird, and lends credence to the "you're just unlucky" theory), is...
1. You're running nothing but pirated copies of Windows.
2. You're lying.
3. You're beating your Windows machines with a hammer.
I can't think of anything else.