crazygazza, The 1.8 converters will only do 160x120, most players will rotate the video when played to use full screen. You need to use Version 4.00 of 3.57. For 3.57 you need to make some manual adjustments as posted
HERE.
If you player does not auto rotate, no fix for this has been found other than upgrading your firmware to a version that does. However be warned that you could kill your player trying to upgrade and you must make a backup of your original software before you try. To do this you need to download s1fwx from the Download>Tools section and there is a guide to backing up your firmware in the Knowledge Base.
You should also read the Dead Player Recovery Guide
HERE so you understand what need to be done if you do kill your player