This plugin takes all the website down!!

Hi!

It means that either your theme or one of the plugins tries to declare the current_page_url() function, without checking if it exists. (the function is already created in Related Posts Lite)

The only possible thing to do here is to find out which plugin tries to re-declare this function. Removing it from this plugin unfortunately won’t help in this case 🙁

Function re-declaration is a common error, mainly with new plugins, when the author forgets to add a checking statement.

If you can list the plugins you are using, I might be able to tell which one is causing it and perhaps suggest a modification to prevent the error.