Vista Home Premium

There is a very annoying behavior on my computer. The issue is that when I
open a window at times it collapses to the bottom task bar. An example is
while composing an e-mail then moving the mouse to send the window might
collapse and one think that the message was sent, however later on you see
the collapse window in the bottom or two days later you see your e-mail in
your draft folder. Other windows will collapse in other program as well.
Currently in the appearance settings are set to Vista Aero. I would
appreciate feedback in order to solve this annoying phenomena!