After acknowledging this dialog box (by pressing OK) i am presented a page with this text:The URL was invalid. Make sure that the protocol is included (http://, https://, or ftp://)
Since this looks like a UNIX expression, I think this message is probably due to having some ',' within it./^(([Ff][Tt][Pp]|[Hh][Tt][Tt][Pp][Ss]?):\/\/[\w\-\.]+(:\d+)?([\?\/][\/\w\.\+\=\:\-\?\%&]*)*)$/
When a ',' is also allowed people can link to specific pages within their site without having SEF enabled.
