Where do I edit this commentarea?

[SWiz]

Hi,

I can't figure out what creates the size (widht) of the commentfield in the bottom
http://www.veggiemind.com/nytt-fran-hal ... klingsmak/

The only thing I can see is:

<textarea tabindex="4" rows="10" cols="100%" id="comment" name="comment"/>
and when I change it in firebug like this. it makes it correct:
<textarea tabindex="4" rows="10" cols="71%" id="comment" name="comment"/>

But where do I edit it?
Or is it something else that creates this, a pluginconflict maybe?
I have made the plug "Wordpress Thread Comment" inactive becuase that one have created conflicts before, but it did'nt help this time.