Windows Not Stay Maximized

In 2000, and in XP, my windows sizes never, ever stay maximized. They always open up to half the screen size. Ths is very annoying. I have done all I could (I am the ADMIN of both system). I have tweaked and resized all I know how, but nothing ever stays maximized. I have to keep doing it (clicking the maximized button) to every window that I open.
I know it is not corruption on both systems because they are both fresh installs.
Please help me and tell me what I need to do.