The reasons for this are historical. What you call the "socialist" elements result from the idea that part of being truly "free" (i.e, liberty) requires that people be treated equally, thus liberals in this sense have a focus on social justice. (See this on "positive liberty": http://en.wikipedia.org/wiki/Positive_liberty .) You can get good summary of differences between meanings of "liberal" in other Wikipedia articles:
http://en.wikipedia.org/wiki/Liberal
http://en.wikipedia.org/wiki/Liberalism
http://en.wikipedia.org/wiki/Liberalism#Classical_and_modern
Because of the way the word's meaning has developed historically, you really need to be aware of the context where it's being used. But there are nevertheless strands connecting all the meanings, namely focus on "freedom" and "equality".