Remember Clippy, the annoying animated icon from past versions of MS Office who would pop up and say things like "it appears you are writing a letter. Can I help?"
The spirit of Clippy lives on in MS products, which of course have become pretty ubiquitous. The spirit of Clippy is evident in features like "smart quotes."
Here's the deal. If you look at something professionally typeset (even a newspaper) and find something in quotation marks, and you look closely, you'll see that the opening and closing quotation marks are not the same – the opening quotation mark and the closing one are mirror images. If you can find an old typewritten document, in contrast, you'll see that the quotation marks are all identical.
Clippy, I mean MS Word, "helps" make your documents more professional by automatically inserting the typographically correct symbols. It isn't just quotation marks. It's apostrophes. It's ellipses (those three little dots that are used to ... uh ... you know). Clippy is busy, converting hyphens to dashes, emoticons to dingbats, inserting bullets, spiffing up fractions, etc.
Here's the problem. Have you ever seen an email message or web page where there are suddenly a few bizarre symbols intermixed with the text? If you looked carefully, you may have even noticed that they occurred where a quotation mark should be. Or an apostrophe. Or a bullet. Or an ellipse. Etc. (See graphic)
Problems happen when your document ends up on a different computer — such as one that has different fonts installed, different character sets for different languages. Problems tend to occur when you copy & paste text from Word into a text-based field — such as when you apply online and you paste your resume into a form field in your browser. Documents that get converted (such as Word to PDF, or web page to email, or Mac to PC) tend to be especially prone to problems. These are exactly the sorts of documents/activities common to the job hunting process!
It's not a big deal. Most recruiters and employers have seen it before, recognize it as a technical bug and gloss right over it. But as someone once said, "a good impression is made up of a thousand details," and this is the type of detail that detracts from a good impression.
Here's the solution. Spend some time in Word's help file (hint: the "autocorrect" feature is the one that's causing all the problems). Figure out how to prevent Word from changing letters, symbols or punctuation marks. (I wouldn't turn off the feature altogether. It fixes typos on the fly quite nicely.)
Bottom line, take control of MS Word. Don't let Clippy mess up your resume!