Logging occurs when HTTP requests are made from Firefox 3 browsers.
Grails 1.0.3 workaround is to open Config.groovy in your project and find the following:
grails.mime.types = [ html: ['text/html','application/xhtml+xml'],
xml: ['text/xml', 'application/xml'], ...
The second line above relating to xml should be deleted.
GRAILS 1.0.3, , . http://jira.codehaus.org/browse/GRAILS-3088 .