why does a thumbnail minimize a browser?

[StickMaker]

I have my Firefox browser window open on my external monitor and Windows Live Mail 2011 open on the main monitor of my lappy. When I move my cursor to the taskbar, and over the email thumbnail on the taskbar, the larger thumbnail comes up. FINE; but WHY does it make the browser window disappear? I believe this is a new "feature" of Windows 7 but so far I don't like it and would like to turn it off if possible. I want the browser window to STAY as is. Thanks!

 

[Bongo]

Try this click on Start button right click on Computer, go to Properties, go to Advanced system setting, Advanced tab under Pereformance hit Settings button, Visual Effects tab uncheck Enable Aero Peek then hit OK close windows .
Jerry
Pics are backwards

 

[StickMaker]

Fantastic, Jerry, fast and accurate. Many Thanks!

 

[Bongo]

Fantastic, Jerry, fast and accurate. Many Thanks!

Your very Welcome glad I could help
Jerry