The only two thoughts I have are. Check in the tv manual as to what is the right resolution to set the picture to. It could be that your video card in the Linx has no reference to that size, in which case you will have to do with the best you can.
On a second thought what is written in the Linx Net-TV box instruction manual about setting resolutions etc?
Also try to Google the TV and The Linx Box and see what help you canget from there. If all else fails ring both the manufactures about the subject they should be able to help, after all they made both the products.