Windows 7: Acer netbook/Windows 7 32 bit...Screen brightness problem ?

Hi,



I have a problem with the screen brightness constantly dimming itself...it doesn`t matter which power setting I try or which route I go down...whenever re-setting,the tab just moves itself back down to the lowest setting...sometimes it stays bright for around an hour and then once again will revert.

I have installed a new hard drive and so this is a new installation of windows 7 32 bit...but prior to this new hard drive I had the same problem.

I have read through similar threads but can`t find a solution so wonder if anybody is able to advise please ? ...all drivers and updates are present on the system.

edit to add...it is the same whether plugged in or on battery.

Thanks,

Is there nobody who has had a similar problem ?