As much as I hate to drag up an old thread im just wondering did anyone really find an answer to this riddle of a problem.
Like many who posted on this I built this rig back about 3 years ago now, and have suffered as a consequence with ET ever since, the problem from my point of view is a kind of random lag type thing that effects the hitboxes of both me and my target, at times I can aim direct at the target and the bullets dont hit? while other times people will aim at me and hit headshots while not aiming at my head, I have installed the dual core optimizer, and amd cpu drivers, and also have threaded optimization off in nvidias control panel, a thing I do notice is the lagometer green line is broken if you understand that, its a very very fine line compared to what I see while specing others but with breaks in it all the time while others seem to have a steady constant line. I wouldnt say its network lag tho as I seem to have a ping around the 46 mark most of the time.
I can only assume its the cpu causing this at the moment.
Specs: AMD AThlon X2 5200+, Nvidia Geforce 9600 GS 1.5gb. 2GB ram
At the moment im running Windows XP SP3 again due to Windows 7 blocking the ET server list constantly.