Ah, now this could also be relaetd to a problem i have had recently. But more on that later, try this...
Go into your menu on your box, and goto settings / TV Screen settings. If you have a widescreen telly select 16:9 otherwise 4:3. (Keep Reading

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HOWEVER, i have an issue in here whereby occasionally the "Set TV Picture signal to: " option changes from Composite to RGB and i have to go in and change it back, when its on RGB the text dissapears just as you say. So change it from what it currently is to the other option and it should work.
I have it set curretly on Composite and it works as it should - with all text on screen, if it defaults back RGB some text gets put off the edge off the screen and i have to go back and change it again.