It seems there are quite a few people who are having disc reading trouble for Xenoblade Chronicles. Well, Nintendo Support has a page for you that better describes why it might happen and what you can do about it.
Nintendo Support 

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Ryan is an owner and manager of the oprainfall website, mostly managing changes needed for the website and maintenance. He also writes articles from time-to-time. His gaming interests include mostly RPGs; both Western and Japanese. Ryan has a graduate degree in psychology.
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