|If Mike's last suggestion doesn't work, I would try these:|
What View are you in? I don't have Word 07, but Print view should show font colors, but the other views may not.
Try printing a new Courier doc to make sure the printer doesn't have a problem with the font.
Copying the old doc to a new doc will also bring over the formattting/corruption, unless you paste without formatting, or clear formatting by using a text editor as a go-between.
You can highlight the offending text, then hit Ctrl-Space to remove font formatting. Try printing.
Check the Paragraph Style, Format/Font, to see if anything weird is specced there.
Check your Options/View to make sure the final document is accurately reflected on your edit screen.