Make sure u D/L the latest drivers from nVidia. When windows autoinstalls them u never know what u get...
other than that i dont really know what u could do to fix it.
Might be some other device interfering, i know my soundcard has been bugging me a couple of times, and that is usually solved by turning off audio hardware acceleration under the Direct X diagnostics menu... Could be worth a try.
Other that just try with low detail levels and see if it chops less then.
Let us know how it works out
