Blu-ray is Blurray, and gives an afterimage effect?

It could be something as simple as your video card being too weak to support the higher resolution on a 42"....but here are other factors to consider first :

Do you have the same issue when playing a blu-ray movie on your PC monitor ?
Do you have the same issue when playing a DVD movie from your PC to the 42" ?
What is your video card ?
What type of cable are you using ?

Are both the TV and video card HDCP (High-Bandwidth Digital Content Protection) compliant (DVI, HDMI connections) for digital output ?

Please add these details & I will try to help you determine the cause.

regards,
Philip T

Is it an LCD?Some lcd tv's have problems with motion blur.Is it only with this movie?Try watching some sports on it and if you see the blur again then it's the tv.

It could be something as simple as your video card being too weak to support the higher resolution on a 42"....but here are other factors to consider first :

Do you have the same issue when playing a blu-ray movie on your PC monitor ?
Do you have the same issue when playing a DVD movie from your PC to the 42" ?
What is your video card ?
What type of cable are you using ?

Are both the TV and video card HDCP (High-Bandwidth Digital Content Protection) compliant (DVI, HDMI connections) for digital output ?

Please add these details & I will try to help you determine the cause.

regards,
Philip T