Hi just purchased this game after playing the demo (Ep 1 demo not the tech demo). The demo ran fine but the full version has some horrible mouse lag. Its just the mouse that lags and it happens in the starting menu too. If I move around with the keys it runs very smooth (I can bang into the lamp and have shadows moving etc and there is no slow down) but as soon as I use the mouse to look around it lags. I have tried many things including turning all the detail down (man it looksugly!), updating AND downgrading video drivers, updating mouse drivers, fiddling with various things in RivaTuner but to no avail. The demo doesn't even work properly anymore either.
I am very disheartened because I doubt you are going to be able to help me and I REALLY enjoyed the demo. Probably have to wait until I get a new computer.
Oh Yeah my specs are
AMD Athlon 64 x2 Dual 3800+
2 GB RAM
GeForce 6600