Did you overwrite the v1.7 bounce.cgi with the v1.8 one? If so, you'll need to (again) modify the 'ListMail URL' within the file. Also, if your host does not support the 'wget' program, used by default by the script, an alternative such as "curl" will need to be configured.
For the v1.7 to v1.8 update, just the files in the main ListMail folder needed to be overwritten - there were not many, if any, improvements to the CGI scripts.
Regards!