I want to get in a server of a friend in 1.7.9, but it gives me a crash report. It's not 1.8.1 but I couldn't change that.

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I want to get in a server of a friend in 1.7.9, but it gives me a crash report.They think it is because I have a mac, but that's not the problem I know. I can't say what the crash reports tells me cuz I ain't a Minecraft expert. Send me a mail if you want me to copy the problem. P.S. I ain't english or American so do not mind if i make some spelling mistakes.