Can't have different applications windows open at the same time

Hi,

For some reason whenever i'm using an application, lets say Chrome, only the windows of chrome would show on the screen. If I click on some other app like terminal, the windows of chrome would dissappear and only the windows of terminal would shop up, so basicially I can't multi task between different applications windows...
This thing usually happens when you press the alt key and press an app on the dock, but not it's permanent and it's really annoying.

What's the deal?
How can I fix this?

using macbook pro late 2008 10.7.3

This thing usually happens when you press the alt key and press an app on the dock

Click to expand...

You're right, that's what it does.

How can I fix this?

Click to expand...

Simple. Don't press the Alt key. If you do that it hides the other App.

I'm not pressing the alt key, that's the thing, it's like it's behaving exactly the opposite.

ISTR several third-party system utility apps that give people this option (hide all but the app I am using, essentially). I wonder if that's what is going on?

(this effect can be replicated by hitting option-command-H when you're in an app with standard hiding controls.)

figured it out! thanks

this site helped me

Set Dock switching mode to 'hide others' by default - Mac OS X Hints