punctuation mysteriously turn into symbols

Within the past hour – most of the apostrophes, commas, quotation marks, html mark-ups and such on my site have mysteriously turned into symbols. This phenomenon seems to run across my entire blog – posts and pages, across all years of my archives.

This has never been like this before. And it renders my blog posts and pages ugly as heck.

Has anybody ever had any experience with this?
Is this a WordPress function – or a hosting function?

I am using 2.7.1 and have never seen this on my blog until a little over an hour ago.