Administrator > Users usergroup_admin.php error

Good Day
Does anyone have a fix for the code generated when i select Administrator > Users.

“admin(<a class=‘link_submit’ ,href =’ usergroup_admin.php?mode =delete_group&id=1’ onclick=‘top.restoreSession()’>Remove) etc”

This was noted after upgrade from 4.2.2 to 5.0.0 then 5.0.1. Every thing else is ok except this.
Not able to group or delete users as a results