I'm a nerd for general grammar. Unless I'm in a big hurry and don't feel like editing, the common misuse of your/you're (and there/they're/their, for that matter) really, really bugs me.
That's why I blame Rihanna for the mass-stupefying of western civilization. The chorus of "SOS," which features the lyric "Y-O-U are making this hard?" I'm perfectly aware that it is technically correct, but it sure sounds like she is spelling out "Your making this hard." Downfall of the masses, right there.
That said, I absolutely love "SOS" otherwise. It is a wonderful pop song that utilizes a sample of Soft Cell's "Tainted Love" perfectly.