I recently bought a used Macbook Pro whose user was Korean and the Macbook itself may have been bought in Korea as well. The OS (Snow Leopard) System language was set to English, so no issues there. Today I wanted to install Lion. I used my USB Lion installer. However, to my surprise, the installer was now using Korean as the language (that is, when I booted into the installer everything was in Korean). Thinking it was still an issue with the previous OS language I terminated Lion installation, booted into single user mode and used 'languagesetup' to change the language again to English (as mentioned here http://support.apple.com/kb/HT4102). This did not help. So I am baffled. Why does the Macbook use Korean when installing Lion, only on this particular Macbook and even though the prior OS system language is set to English? Is there some information in hardware that determines the default installation language? Update: I tried to get around this problem but it kept reoccurring. No matter what, I was not given the option to choose system language during Lion install and it would always default to Korean. What seems to have fixed it in the end is (a combination of) the following: 1) I had to reset PRAM. 2) I used the languagesetup to again change the system language to English (from my "blind" Korean installation of Lion). After this I was finally offered the option to choose the system language upon USB Install boot. Really, really odd.