Minecraft 1.4.7 Consistently Crashing from Multiple Commands

When in any of several created worlds a number of different keys/ commands cause the application to crash so we basically cannot use this software at all. Here are the ones that cause it to crash: Open Inventory (uses R key right now, but still crashes when you assign a different key to that command), Talk (uses T key), Command (uses B key), Home (Escape key).

Please help-- is there a patch we can download? Is this mac specific? If not can I get a refund?
Thanks,
Nick