Authentication Class.FeedBack Please.

[PlaGuE]

This is an Authentication Class i am working on.

I'd appreciate any feedback on making improvements to its security.

<?
class AuthClass{
    
    function Exeption($Error = array(), $BREAK = true){
            $this->ErrMessage = "";
            if($BREAK == true){
            $this->ErrMessage = "<br />";
                foreach($Error as $Err){
                    $this->ErrMessage .= "<br /><strong>Portal Error</strong>:".$Err." \n";
                }
                  return  trigger_error(exit($this->ErrMessage));
            }else{
            $this->ErrMessage = "<br />";
                foreach($Error as $Err){
                    $this->ErrMessage .= "<strong>Portal Error</strong>:".$Err." \n";
                }
                  return  print("".$this->ErrMessage);
            }            
        }
    
    function Authentication($mRank){
        // Authentication Functrion
        if(isset($_POST['AuthLogin'])){
                if($_POST['userName'] == NULL || $_POST['userName'] == ""){
                    $AuthErrors[] = "You Need to Input A UserName.";
                }
                if($_POST['passWord'] == NULL || $_POST['passWord'] == ""){
                    $AuthErrors[] = "You Need to Input A PassWord.";
                }
                $DUserName = stripslashes(htmlentities($_POST['userName']));
                $DPassWord = stripslashes(htmlentities($_POST['passWord']));
            $result = mysql_query("SELECT * FROM users WHERE username='".$DUserName."' AND password = PASSWORD('".$DPassWord."')");
                      if(mysql_num_rows($result) == 0 ){
                              $AuthErrors[] = "You Have Specified An Incorrect UserName/Password.";
                      }
                      extract($userinfo = mysql_fetch_object($result));
                        if($_POST['RememberMe']){
                              setcookie("CuSeR",$userinfo->username, time() + 3600);
                            setcookie("CuSeR_ID",$userinfo->ID, time() + 3600);
                        }
                        $_SESSION['CuSeR']    =    $userinfo->username;
                        $_SESSION['CuSeR_ID']    =    $userinfo->ID;
                        $_SESSION['CuSeR_Rank']    =    $userinfo->rank;
                        $_SESSION['CuSeR_LastLogin']    =    $userinfo->lastlogin;

        }
        if(isset($_COOKIE['CuSeR']) && isset($_COOKIE['CuSeR_ID'])){

            $result = mysql_query("SELECT * FROM users WHERE username='".($_COOKIE['CuSeR'])."' OR ID='".$_COOKIE['CuSeR_ID']."'");
                      extract($userinfo = mysql_fetch_object($result));
                        $_SESSION['CuSeR']    =    $userinfo->username;
                        $_SESSION['CuSeR_ID']    =    $userinfo->ID;
                        $_SESSION['CuSeR_Rank']    =    $userinfo->rank;
                        $_SESSION['CuSeR_LastLogin']    =    $userinfo->lastlogin;

        }
//*
        $result = mysql_query("SELECT * FROM users WHERE username='".$_SESSION['CuSeR']."'");
        extract($userinfo = mysql_fetch_object($result));

            //print("My Rank:".$userinfo->rank."<br />");//-Making Sure
            //print("Needed Rank:".$mRank."<br />");//------Rank Checking Works

                    if(!$userinfo->ID){
                        //return false;
                        $this->Exeption($AuthErrors,false);
                        $this->loginForm();
                        }else{
                            if(($userinfo->banned == 1) && ($userinfo->verified != 1)){
                                $this->Exeption(array("Not Only are you not a verified user, but you are also banned."),false);
                            }
                            elseif($userinfo->banned == 1){
                                    
                                    $this->Exeption(array("You Are Banned"),false);
                              }
                                elseif($userinfo->rank >= $mRank){
                                    if($userinfo->verified != 1){
                                        $this->Exeption(array("You Are UnVerified"),false);
                                    }else{
                                        return 1;
                                    }
                                }else{
                                     $this->Exeption(array("You do not have a high enough rank to view this page.<br />\n"));
                                }
                    }


    }//End Authentication Function

        function loginForm(){
        ?>
<style type="text/css">
<!--
.style3 {
    font-size: 10px;
    font-family: Geneva, Arial, Helvetica, sans-serif;
    color: #FFFFFF;
}
-->
</style>

        <form action="<?=$_SERVER['REQUEST_URI']?>" name="AuthLoginForm" method="post">
        <table width="31%" border="0" align="center" cellpadding="0" cellspacing="1" bgcolor="#000000">
  <tr>
    <td colspan="2" bgcolor="#999999"><div align="center">Login</div></td>
    </tr>
  <tr>
    <td width="8%" bgcolor="#999999">Username</td>
    <td width="92%" bgcolor="#999999"><input name="userName" type="text" value="UserName" class="login_text" /></td>
  </tr>
  <tr>
    <td bgcolor="#999999">Password</td>
    <td bgcolor="#999999"><input name="passWord" type="password" value="Password" class="login_text" /></td>
  </tr>
  <tr>
    <td colspan="2" valign="middle" bgcolor="#999999"><div align="center">
      <input type="submit" name="AuthLogin" value="Submit" />
      <span class="style3">Remember Me?</span>
      <input type="checkbox" name="RememberMe" value="true" />
    </div></td>
    </tr>
</table>

        </form>
        <?
        }
    }
?>