Try unseating all the cards, rebooting the controller and watch the LEDs on the backside if you can see them, then try to connect with Manager. I had a similar situation where a bad port on one of my cards locked everything up. If you can connect at this point, take a complete download in case you have to reformat your SD card, but try re-seating all the cards one at a time to determine if any of the cards is causing your failure.

If no changes, reformat as Mongo suggested.

Sometimes the thoughts in my head get so bored, they go for a stroll through my mouth. This is rarely a good thing.