2300MP showing white vertical bar

A flickering white vertical band has started to appear on the screen. It is most noticable during moving videos. It started off as a few pixels flickering in the middle top of the screen (a block of about 16x32) and has degraded to being the entire vertical column down the center of the screen. Still pictures show up the band less then movies but it is there in both cases.

Tried using VGA and composite video inputs from a number of sources (laptops (Widows and Linux) and a DVD player). Changed all cables. None of the changes effected the problem. Symptoms progressivly getting worse.

Any help welcome

UnderMine