Several programs can prevent the app switcher and charms from appearing when you move your mouse to the corners of the screen in Windows 8, but you can do it yourself with this quick registry hack.
You can also hide the charms bar and switcher by installing an application like Classic Shell, which will also add a Start menu and let you log directly into the desktop.
Editing the Registry
First, open the registry editor by pressing the Windows key, typing regedit, and pressing Enter. Click Yes when the User Account Control prompt appears.
Navigate to the following registry key in the registry editor:
Right-click the ImmersiveShell key, point to New, and select Key.
Name the key EdgeUI and press Enter.
Right-click the EdgeUI key, point to New, and select DWORD Value.
Name the value DisableTLcorner and press Enter.
Create another DWORD value in the same way and name it DisableCharmsHint.
Double-click the DisableTLcorner value, type 1, and press Enter. This disables the top-left hot corner, which activates the switcher by default.
Double-click the DisableCharmsHint value, type 1, and press Enter. This disables the top-right and bottom-right hot corners, which reveal the charms bar by default.
To undo your changes and restore the hot corners in the future, right-click the DisableTLcorner and DisableCharmsHint values you created and delete them.
Note that this will only disable the hot corners themselves. if you move your mouse to one of the corners and then move it along the edge of the screen to the middle of the screen, the switcher or charms bar will appear.
To quickly access these features after disabling the hot corners, press Windows Key+C to open the charms bar or press Windows Key+Tab to open the switcher.