FYI (for others), I addressed this issue in email. For those who also get this error, here's an explanation as to why it will usually happen:
beardie":1zj5xaak said:
My guess is that you're trying to copy and paste the content from some other document. This error is the system complaining that something other than regular text was entered into the post form. This commonly occurs when someone copies and pastes from Word, or even an email client, where Windows has inserted a non-standard text quote mark or some other thing like that. Try copy and pasting it into Notepad first and removing any characters that are not the basic ASCII text. That can usually solve the problem. If it's short enough, just type it out.