Ok, I think I have to apologize:
As I tried to save dxdiag infos, dxdiag hung and i rebooted the machine. suddenly echoes works perfectly

So after all, it was a stupid fault. And I guess, I know, why this happended:
I haven't restarted the machine for at least 3 weeks, but sent it to SuspendToRam every night. Windows (as far, as I know) has
a time counter, which give you the time since the last boot. And I guess, the game uses this timer and couldn't handle the way-too-big
values returned. Maybe you should check this (although it's a quite seldomly seen problem, as most people shut down their machines regularly)
thanks anyway!
shamada