Electric windows wind down in the middle of the night!?

I am experiencing a weird problem with my Vectra 2.2 Direct (05 reg). A couple of days back the alarm system started cutting in a few minutes after it had been set. I have had to revert to manual locking, BUT for some inexplicable reason the electric front windows wind down antime between a few minutes after locking to hours after it has been locked. I am getting to the stage where a disconnect of the car battery is the only
alternative until I sort the problem out!! Am I missing something simple here? I should add that it all started after replacement of the key remote battery.