accidentally changing keyboard layout

[ernest]

Hi,
Recently, I've been compelled to use the Windows (XP) operating
system.
The problem I have is that every now and then I change emacs's
keyboard
layout by accident. Usually it switches to US layout, some times to
other
layouts. It must be some combination of keys, I still haven't figured
out which ones. Once it's changed I cannot fix it or I don't know how
to fix it.
I select the default keyboard layout or the Spanish layout on the
menu, but
nothing happens. I have to restart emacs every time!
Any idea how I can avoid this? This is specific to emacs, other
programs
are not affected. I also use emacs on GNU/Linux and never had this
problem. Cheers.
--
Ernest