I had the same, nothing worked, until I changed the start-up setting of my DSN from manual to automatical.
this can be changed after pushing the small DSN icon at the middle bottom. no problem since then.
bert, November 2010
i take it you are using a DS? if so take the cart out and blow on the connectors (crazy it sounds but it works) and dont use an eraser use a little alcohol on a cotton wool bud and wipe this over the cart connetors
jason, January 2010
It was probably just dirty, but by "cleaning" it with an eraser you might have ruined it.
