maximized

i know this was posted somewhere but cant find it ... how do i enable aero when my window is maximized

i hav xp sp2 pro installed on my laptop...after few repairs when it came back to me when i open my folder windows they dnt start maximized and open with reduced size ..i hav to manually clik each window's maximize button to maximize it to full screen,... wat cud b wrng? how 2 slve it? so dat...

Whenever a new window is opens its not directly maximized. is there n e option that whenever we open a new window it is by default maximized so that each time i do not have to click on the maximize icon lemme know!