@boomerang,
Maybe they'd been on the store shelves for a while, or had been bulk stored at a warehouse for too long, who knows?
I know this might not sound too wonderful a solution to your problem, boomer, but this is what I'd be tempted to do in your situation. To avoid boiling the crap out of everything else in the dish you're cooking, I'd extract the beans (using a big slotted spoon or something similar - messy, I know ..) & microwave them separately, within an inch of their lives! (I know some folk object to microwaves, but not me.)