video lag on my new Sony LCD

[bone crusher]

Okay I'm still a little new to LCD and what exactly 120hz etc is but help me out with this minor problem. I'm runnning Blu-rays on my PS3 through HDMI to my Sony KDL-40D3000.

To me my tv is presenting to me what is video lag, or at least that's what I'll call it. I notice on the movies that every once in a while I see the picture almost jitter like something is running either few frames behind or few frames ahead. The picture doesn't look completely convincing. My tv has 120hz capabilities. I gave experimented with the tv's feature of "motion enhancement" by turning it from off to standard to full and seem to have this "lag" with any of these settings turned on. What could this be? Is the "motion enhancement" feature on my Sony tv actually the 120hz feature itself that I am adjusting? Or is the 120hz just somethig that is running all the time now matter what?

I am aware that LCDs in general have what has been traditionally been called "motion blur" etc on them but to me this tv with 120hz shouldn't have that anways as I thought 120hz alleviated that problem??

I have watched movies on other peoples LCDs before and never noticed anything that I would cal motion blur or lag and those LCD tvs didn't even have the 120hz technology.

Could this just be a setting within my PS3 that is causing this visual imperfection?

Thanks and any help on this matter will be greatly appreciated.