Before you say its just the computer, or its another add-on you have. It's not. With my old Macbook I installed just Blockland, ran it, played a game for about 20 minutes and it worked fine. Downloaded RTB, played a game for about 5 minutes and it froze the whole computer. So I thought it was just my computer. Then I got a 2009 iMac 27 and I did the exact same thing. Tried it with and without RTB. It froze about 5 minutes playing a game after RTB was downloaded. So for the sake of test I tried this exact same thing on my mom's Macbook air pro. Same results. I'm just wondering if I download windows for my iMac will RTB stop doing this? I believe RTB was a exe file which Mac doesn't support.