Irregular key mapping?

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http://askubuntu.com – Any better title is welcome. All of a sudden when I press: d - I either see d typed in or I get a print screen window e - I either see e typed or I see volume bar rise c - I either see c typed or I have many different effects (depends on context) So far I'm unable to tell what is the "trigger" or "toggle" for this peculiarity. I'm frankly at a loss what to investigate. Few findings: - while this first manifested in a browser (FF + Vimperator) this is NOT browser limited - GVim, terminal even tty (I switched to it) can have that - In tty d becomes \; and c becomes ^[[5~b and presses Enter. (HowTos)