You may well have come across (and possibly been infuriated by) the 'swipe' feature in Windows 8 where you make an everyday sweeping mouse movement and get flipped to another window.
Good news : you can turn off this feature.
First get to the Control Panel. Windows 8 does not, of course, make this easy or obvious for you but:
Right click on the 'Start' button (bottom left) then select Control Panel.
then go to Mouse
pick the top right tab Device Settings
highlight the (usually) only entry
uncheck Enable edge swipes
Close the various Control Panel windows and you are all done!