Bad character in AJAX response?

I make an AJAX call and in response, I return some lines of text using ASP.NET.

But sometimes the response does not show completely in IE7 (but OK i开发者_运维问答n Firefox).

I think there is a bad character in response. Is there a list of bad characters or any rule to create standard response?

Just wrap any text in the xml node with <![CDATA[ ... ]]>