1. xHTML hataları var.
2. if, else'den sonra ; konulmaz.
3. Mutlaka kod düzeni edinin... (Canımı çıkaran nota bu. )

<?php
session_start();
include('ayarlar.php');
if (isset($_SESSION['_kadi']))
{
	$sql = select * from _user, _bakiye,_kultip where _kultip._no=_user._durum and _user._id=_bakiye._kid and _user._kadi="".$_SESSION['_kadi']."'";
	$sonuc = mysqli_query($baglanti,$sql);
	$fields = mysqli_fetch_assoc($sonuc);

	echo '
	<table cellpadding="0" cellspacing="0" width="100%" class="girisss">
		<tr>
			<td width="35%" style="text-align:left; padding-left:35px;">
				<table>
					<tr>
						<td><img src="tema/resim/giris-gpbakiye.jpg"/></td>
						<td valign="middle"><b style="color:#444444;font-size:11px;font-weight:bold">'.$fields['_bakiye'].' TL</b>&nbsp;&nbsp;&nbsp;&nbsp;</td>
						<td valign="middle"><img src="tema/resim/giris-gpbonus.jpg"/></td>
						<td><b style="color:#4aa515;font-size:11px;font-weight:bold">'.$fields['_bonus'].' TL</b></td>
					</tr>
				</table>
			</td>
			<td width="40%" style="text-align:left"><b style="text-transform:capitalize;color:#444444;">Merhaba,&nbsp; '.$_SESSION['_kadi'].' </b> &nbsp;<img src="tema/images/bullet.gif"/><em style="text-transform:capitalize"> '.$fields['_adsoyad'].' -&nbsp; '.$fields['_tip'].'</em></td>
			<td width="25%"><a href="profil.php"><b>Kullanıcı Profili</b>&nbsp;&nbsp;&nbsp;</a><img src="tema/resim/imlec.png"/> &nbsp;<a href="kutuphane/logout.php"><b>Güvenli Çıkış</b></a></td>
		</tr>
	</table>';
}
else
{
	echo '
	<form method="post" action="">
	<a href="register.php"><small>Üye olmak için Tıklayınız! </small></a>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
	<a href="javascript:openpopup(\'sifremiunuttum.php\')"><small>Şifremi Unuttum</small></a>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;';
	if (isset($_GET['hata']))
	{
		echo '
		<span id="farbwechsel"><font size=1><B>HATALI GİRİŞ !</B></FONT></span>
		<script language="JavaScript">
		function wechsel1(){document.getElementById("farbwechsel").style.color = "RED";window.setTimeout("wechsel2()",700);}
		function wechsel2(){document.getElementById("farbwechsel").style.color = "BLACK";window.setTimeout("wechsel1()",500);}wechsel1();
		</script>';
	}

	echo '
	<span><small>Kullanıcı Adı: </small><input name="kullanici" type="text" value="" maxlength="20" class="inputTextbox"  /></span>
	<span><small>Şifre: </small><input name="sifre" type="password"  value="" maxlength="20" class="inputTextbox" />&nbsp;&nbsp;&nbsp;</span>
	<input name="kgirisi" type="submit" id="kgirisi" value="Giriş" class="inputSubmitBtn" />
	</form>

	burası 49uncu satır........................';
}
if ($_POST['kgirisi'])
{
	$kadi = $_POST['kullanici'];
	$sifre = $_POST['sifre'];
	$sql = "select count(*) as _count from _user where _kadi='".$kadi."' AND _pass='".$sifre."'";
	$link = mysqli_query($baglanti,$sql);
	$fields = mysqli_fetch_assoc($link);
	if($fields['_count'] > 0)
	{
		$sql = "select * from _user where _kadi='".$kadi."' AND _pass='".$sifre."'";
		$link = mysqli_query($baglanti,$sql);
		$fields = mysqli_fetch_assoc($link);
		if($fields['_durum2']=='true')
		{
			$_SESSION['_kadi'] = $fields['_kadi'];
			$_SESSION['_durum'] = $fields['_durum'];
		}
	}
	echo '
	<script>window.location="', $_SERVER['REQUEST_URI'], '";</script>';
}
?>