"Derefer/Detect External URLs" was generation an error on one of my topics in which a user replied, and so i had to deactivate it. The user had a url code on his signature:
Code:
[ url="http:///"]x[ /url] (with no spaces)
The error was:
Code:
Warning: parse_url(http://): Unable to parse url in /includes/class_bbcode.php(149) : eval()'d code on line 38
Hope this helps.