Wrong cursor icon used when hovering over text in comments.

When I am viewing comments on my site, the mouse cursor remains an arrow while hovering over text, rather than being the "text" cursor (the I-beam thing).

I am using Firefox 3 on Windows. If I modify the CSS on my site and add this rule, it works correctly:
* { cursor: auto !important; }

Which tells me that Intense Debate is setting the cursor CSS property for some reason.

This is probably because you are setting it to "default" rather than "auto" somewhere. "default" means system default (the arrow), not the webrowser's default. "auto" means the web browser decides which cursor to use.