Comment 8 for bug 1080789

For somebody experiencing this, can you please try adding/modifying your /etc/X11/xorg.conf as follows, or create a suitable /etc/X11/xorg.conf.d/xyz.conf script:

Section "Device"
    Identifier "Tegra"
    Driver "tegra"
    Option "ARGBHWCursor"
EndSection

If this resolves/works-around the corruption, you'll also want to adapt the following kernel patch to resolve console errors when the cursor moves off-screen:
http://nv-tegra.nvidia.com/gitweb/?p=chromeos/kernel.git;a=commitdiff;h=b50bf5979036750891461a5824bb12273f04fe16