arduino sketch on Win7 vs. MAC op system?
I've had the same issue with Mac OSX 10.6.8 vs Windows XP SP3 using the same IDE version. I don't have a definitive answer for you, but I know that Microsoft has more frequent updates compared to Apple, which could be the reason. I suspect my issue and your friend's issue is the GCC compiler we're using. The compiler would be updated on OSX only when you update your entire OSX version. To get around that, there are third-party package managers: Homebrew and MacPorts that would allow you to just update the GCC compiler for example.