the explaination I read off the Prevx site for the blackscreens is

BTW the cause of this recent crop of Black Screen appears to be a change in the Windows Opertaing Systems lock down of registry keys. This change has the effect of invalidating several key registry entries if they are updated without consideration of the new ACL rules being applied. For reference the rule change does not appear to have been publicised adequatley, if at all, with the recent Windows updates.

I have not had any problems with blackscreens an it makes me wonder if the problem is not with Windows but rather with security software like Prevx needing to be updated interesting read anyway I have never heard of Prevx before this story and the conspiracy theorist in me thinks that Prevx on some level likes the free publicity the interest in a story like this will generate