Windows 7: Application windows position not remembered

Hi All!

I use a Dell Latitude E5520 laptop with docking station and a Dell LCD monitor. The Dell monitor is the main screen with the traybar on it, the built-in laptop monitor is the secondary.
Applications like Outlook, Excel is on the main monitor, some apps like communicator, windows explorer, etc are on the built-in screen. This is my default layout. When the laptop goes to sleep after work and I start using the laptop next day, the apps windows are on the same place, where I left.
Problem is, when I remove the laptop from the docking station. Of course this time everything appears on the built-in laptop monitor, since there is no other attached display. But, when I place the laptop back onto the docking station, every app window goes back onto the primary display, which is the Dell LCD. To me colleagues the apps windows appear on the same place, where they previous were, while the laptop was on the dockin station, e.g.: if the communicator was on the built-in display, then it appears on it, if the Outlook was on the primary display (Dell LCD), then it appears on the primary display.
So my Windows doesn't remember the position of the apps while the laptop was on the docking station and being put back on it, which makes me very nervous, because every time I put back my machine to the docking station, I have to drag and drop for example the communicator (and other windows) to the secondary display.

Anybody can help me how to make Windows 7 Prof x64 remember (and make difference) the windows position while the laptop is on the dock or being removed?

Thanks for your help in advance!