Windows 7: Black screen with working mouse on opening comp or closing session

Hey guys.
I got a Asus laptop running windows 7 Family Premium edition 64x



I don't know how it started, but someday and somehow i tried changing session, the session closed, but the blue screen where i choose session never open. But i got the mouse moving but nothing to click on.
Even if i force closing the the laptop, when the computer get to the session page i get a black screen with working mouse.

The only way i found to counter that is to force closing the computer while windows is loading so i can then load the repair manager (or w/e the real name is) So i load a later copy.

Then my laptop can work 6h like 2 day without having problem when changing session or restarting the computer.

And i've just had a problem doing the crtl+alt+del. when i just rebooted the comp i can do it, but when the problem is about to happen i cant open the crtl+alt+del and i get an error message (i'll post it next time it happen.)

I've look for the Shell value in Regedit cause it been a solution and my value is still good.

Hope you guys can help me

thx