lock/unlock with command-E doesn't work

Todd Harrop's icon

I've used Max for a couple years but suddenly the hotkey 'command-e' became disabled. I can still lock and unlock from the pulldown-menu but not with a keyboard shortcut. Why? This is quite annoying. Please help!

Todd Harrop's icon

…OK, it was because of another app running concurrently (a dictionary), and the cmd-E was hijacked by it.