curves on screen

[dumbass]

i have a 28" furguson flat screen tv about 2 years old and ive noticed that any straight line runs off at a slight curve away three quaters up the edge of the screen, ive tried every setting making sure the ratios are the same as my panasonic free view box and all settings are compatible, but know matter what setting its on the curves are still there, has anyone had got any sudgestions as what could be the fault,