As descibed here
http://www.titanquest.net/gameplay/8...html#post79104
My friend has this problem too. His graphic-card is a GF4 Ti4600.
Turning shadows off = terrain (floor) has dark and bright areas, which are "seperated" with some kind of boundary - sharp lines between them. On the one side of thet "line" the terrain isd dark, on the aother side its bright. Or the dark side swiches to bright when walking over that "line". Game runs smoother, even if changing texture and detail level to high, but terrain-bug is still present
Turning shadows on = everything is fine but laggy in internet mp.
For me it works fine - i have a GF5 5700Ultra. Settings in Nvidia-driver and ingame-options are the same on both pc.