I have fixed the author issue recopy the msg in forum code, and here is a tutor on how u cn set ur comment box invisible for non-logged users..
1st Go To Forum Bottom Autocontent And Paste Two Code below

<style>.log{display:none;}</style>

And Give The Item Visible "Non-logged User" Save.. Open Another Wml/Xhtml Code In Xame Forum Autocontent Bottom And Paste This

<style>.non-log{display:none;}</style>

And Give The Item "Visible For Logged User Only" Then Go To Message In Forum And Search ::REPLY_AREA:: In 3rd Box And Replace ::REPLY_AREA:: To

<div class="non-log"><div class="notif">You Must <a href="login_0.xhtml">Login</a> Or <a href="registration_site.xhtml?do_id=0">Registration</a> To Comment.</div></div><div class="log">::REPLY_AREA::</div>

Then Click Set To Save.