Nokia :: 2330 Classic / White Display On Standby

I've searched on Google till page number 15 but no one had written something on my problem.I have 2 nokia 2330 classic, 1 for my father and 1 for my mother (both taken with Vodafone points). They are new.Both of them have the same strange problem. They work correctly, but when you leave the phone in a standby mode (so as it can be in your pocket during the day) the display became completely white (after a little bit of time). And it remain white till you push a button.You can imagine that this is a problem for the battery, because when the screen is white the phone sucks a lot of charge.The strange thing is that both of them had the same problem.Is there anyone that has the same problem?Is there anyone that is able to solve this problem?