This is probably a conflict with another plugin or theme. Disable all your plugins and use the default theme, then enable your plugins one at a time until you find the one causing the conflict.
Also, check in your discussion settings to make sure your comment settings are set properly.
I have the same problem and I’ve tried all of the above.
Try accessing the settings by going to Settings -> Rizzi Guestbook. Right now the link from the plugin page is broken which is why you are receiving that error. I am sorry about the inconvenience. I will be fixing it on the next update, which hopefully should be within a week. If you are still having issues, you can get to the settings page by entering this in the address bar of your browser. yourwebsite.com/wp-admin/options-general.php?page=rizzi-guestbook
I hope this was helpful.
Same here.
Ling in Plugin Site to settings does not work.
Target of the link url is /wp-admin/options-general.php?=wp-vipergb
Maybe it is helpful.
Thanks for fixing soon.
Tom
