Ok, I've installed Windows 8 and examined it.
WA works in frontend, but crashes once you start a match, and the errorlog isn't created too (because it is a Windows appstop error).
Then I tried launching it with Project X, and the match started just fine! Most likely because of Project X's Direct X integration. However it crashes after a match, because the game must return to frontend.
I can give you the screenshots if you wish.
Update from 18.12.2011: after some tries, it WORKS on Windows 8, without PX or anything! Double buffering fixed the black screen, but I still don't know what fixed the App Crash.