Black Screen

can you provide some more info plz so we might get a better understanding of what your situation is..

Is your phone stock? (have you installed any third party apps)
Does this occur after long periods with a soft reset?
Are you using any screen lock software such as S2u2?
Are you closing apps or leaving them open? (could just be a case of your phone being out of free mem)

Is your WiFi on when it goes to sleep?

If so, it has to finish re-connecting or searching networks every time its woken up again, an will stall the screen refresh doing it.

WR

There is a way to enable it to keep Wifi alive in registry, it used to be on by default then it wound up in a tweak program to disable it as some would forget an come back to a dead pda, then WM set it to default Wifi off when screen goes off.

I'm not %100 sure, though I think ATC, Advanced tool configurator 3.0 or 3.3 something like that has the ability to set this back to on, I believe if I remember correctly.

Maybe take a peak if you want it to stay on in your case.

WR