I just upgraded to Ubuntu 12.04 (from 11.10) and I am the Desktop Wall Plugin from Compiz. My bindings for Move Left, Right, Down and Up are Ctrl plus the corresponding arrow key. Since the upgrade, when I press Ctrl and an arrow key my background image is visible for an instant and then the desktop is switched. This is very annoying as my background image is very bright and flashes me every time.
If I switch my desktop and hold down the Ctrl key and press another arrow key the glitch does not occur.
Is there any workaround for this?
It seems like a conflict with another Shortcut. Try to isolate your keys to a funcion. I have solved a conflict using Super (Windows) Key + Directional Left, Right, Up and Down Keys to do Viewport Switching (Desktop Wall or Virtual Desktop Switching) just by isolating Super Key from being used to call Unity Launcher (default behaviour is to press Super Key to do it). I changed it to something else, and voila, desktop switching without pressing Enter Key.
Since you seem to be used to switch between workspaces via the keyboard I suggest two workarounds:
a) choose viewport directly
Use Compiz' plugin "Viewport switcher". You can set it to choose your workspaces directly, e.g. Ctrl+Shift+1 for "Switch to Viewport 1".
b) coose viewport from overview
Use the Workspace Switcher from the launcher. You can access it via Super+S, too. Then, with arrow keys, select the workspace you want to switch to and press Enter.
This glitch seems to be gone in Ubuntu 12.04.2.