Quotation marks look like " " in one InDesign document

Question

At my job I am updating an old InDesign file in CS5 with new content. Whenever I press the " or ' I get >> or > (not exactly, but it's a symbol that looks very similar to  >> or >). I have never had this problem and can't understand why it is doing this. There is nothing else in the document that makes the wrong symbol when the key is pressed.
I am using a Mac and none of that stereotypical IT advice helps (reset the computer, open and close the program, etc.)
I also already went into preferences & selected typographer's quotes, then changed the quote settings in Preferences > Dictionary to be the correct typographer's quotes, but it makes no difference. I feel like this should have been the solution to the problem.
Any ideas? I'm getting tired of making the proper quote mark in another document and copy-pasting it whenever I want to use one (the only thing that works).

Answer 1

Never mind, I googled it based on M Blackburn's response and found the solution myself. I will now explain the solution in case anyone else who was wondering stumbles across this.
The correct solution is:
1. Select the text and go to the Character panel.
2. In the Character panel at the bottom there is a drop down that is marked Language. If you have selected the text and the current selection of the dropdown is blank, it means there are multiple languages being used (in my case, somewhere in the document the original author of the document accidentally used French, I guess).
3. Change the drop down to "English: USA".
I had already changed the language and both the quote options in the Preferences > Dictionary section, and this didn't change anything. The French apparently overrides it.
M Blackburn was right about it being French, but Bob Levine of course that's the solution... I wanted to know how to do it, and Jeffrey_Smith I said earlier that I already tried that. Please double-check your answers to make sure they are worthwhile!