[Lynne]

Looks like the message width is set using this css:

.standard_error {    margin: 0 auto;    max-width: 600px;    padding: 4em 0 6em;}

And, is that the registration page? (clicking the image just shows the same size image, so I can't tell). The width for those is from this CSS:

.vbform {
clear: both;
margin: 0px auto 2em;
max-width: 750px;
width: auto;}