I'm guessing it's due to the refresh rate, which the 360 defaults to 60hz. 60hz is much too low for most people when it comes to CRT monitors. 75hz is apparently the minimum to reduce eye strain. Could this be what is causing the headaches? I don't get the feeling when playing on any other display type, or even on 60hz CRT SD and HD television sets.

I dunno, nausea and sickness are pretty extreme for 60 hz. Are you playing at an odd viewing angle, in an uncomfortable chair, very dark room, etc?

I get nausea sometimes with my CRT when playing fps PC games. It seems to only be certain games though. I thought maybe it was due to a low, stuttering frame rate. My refresh rate is above 75 hz so I can probably rule that out for me anyway. I sometimes hook up my PC to my HT display which is a plasma and I have no problems with the same games and same framerates. So I am kinda wondering the same thing.

I dunno, nausea and sickness are pretty extreme for 60 hz. Are you playing at an odd viewing angle, in an uncomfortable chair, very dark room, etc?As I said, I don't get this issue at 60hz with CRT televisions, it only seems to occur with CRT progressive scan PC monitors.

Is there maybe a scientific explanation for why 60hz is too low for progressive scan CRTs? I've read in most places that 75hz should be the minimum on CRT monitors. I am not sure why this is true for monitors though and not TVs. My guess is it has something to do with being progressive vs. interlaced.