Deactivate the taskbar button combining

Windows 7 have a nifty feature which combines the windows of opened applications under the same taskbar button. If you don't like it you can always turn it off.

By default, when more windows of the same application are opened, the application groups under the same button on the taskbar.

Right click the taskbar.

And choose Never combine as a Taskbar option.

That's all. All running applications will now have their own taskbar button.