You can't/shouldn't mix SELECT *
with the selection of individual fields.
If you are going to select individual fields (which you SHOULD do and you are doing), then kill the * part of the SELECT.
Anyway, time to DEBUG DEBUG DEBUG. Stop trying to do everything in one statement. Break it up so it's debuggable.
$sql = "SELECT P.mem_id, P.com_memid, P.comment, P.com_approved, P.com_time, "
. "A.adv_paused, A.adv_approved "
. " FROM profile_comment AS P INNER JOIN adverts AS A "
. " ON P.memid = A.adv_userid "
. " WHERE P.com_memid ='$USERID' "
. " AND P.com_approved = 1 "
. " ORDER BY P.com_time DESC";
echo "<hr/>DEBUG SQL: " . $sql . "<hr/>\n";
$iscomment=mysql_query( $sql, $link ) or die( mysql_error( ) );
So first look at the debug output to be sure it is what you expect. In particular, is the value of $USERID correct?
If you get an error from the "or die", then what is the error?
And if you copy/paste that SQL into a query tool, what does it give you?