Error after atualization

[Mastrocolla]

I'm from Brasil and I'm new on the linux world.
(Sorry if my English is bad).

So, I've installed Ubuntu 10.4.1 and W7 and they worked pefectly.
But yesterday after an atualization W7 becomes to shutdown suddently, a black screen appears and the HD stills running.
I observed that when I shutdown Ubuntu the same thing happens.
How can I solve this whithout reinstalling both OS?

Gotcha?

Thanks