I've had a Toshiba 32ZP18Q for 18 months - very happy with it - but several buttons on the remote control have suddenly stopped working. These include the Teletext, MENU, Screen size and EXIT (ie the Texttext plus the row of 4 buttons between the number pad and the arrows) All others are OK. The left slider button is set at TV OK. Anyone any ideas what could be up or suggest checks I could make? Ta.