Index: kernel/globals.php
===================================================================
--- kernel/globals.php	(revision 14103)
+++ kernel/globals.php	(working copy)
@@ -362,7 +362,11 @@
 			curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
 
 			curl_setopt($ch,CURLOPT_REFERER, PROTOCOL.SERVER_NAME);
-			curl_setopt($ch,CURLOPT_USERAGENT,$_SERVER['HTTP_USER_AGENT']);
+
+			if ( isset($_SERVER['HTTP_USER_AGENT']) ) {
+				curl_setopt($ch, CURLOPT_USERAGENT, $_SERVER['HTTP_USER_AGENT']);
+			}
+
 			curl_setopt($ch,CURLOPT_FOLLOWLOCATION, 0);
 			curl_setopt($ch, CURLOPT_TIMEOUT, 90);
 
Index: kernel/session/inp_session.php
===================================================================
--- kernel/session/inp_session.php	(revision 14103)
+++ kernel/session/inp_session.php	(working copy)
@@ -117,11 +117,14 @@
 			'PortalUserId'	=>	$this->Application->isAdmin ? 0 : USER_GUEST,
 			'Language'		=>	$this->Application->GetDefaultLanguageId(true),
 			'Theme'			=>	$this->Application->GetDefaultThemeId(),
-			'IpAddress'		=>	$_SERVER['REMOTE_ADDR'], // getenv('REMOTE_ADDR') won't work on IIS, so use $_SERVER instead
 			'GroupId'		=>	$this->Application->ConfigValue('User_GuestGroup'),
 			'GroupList'		=>	$this->Application->ConfigValue('User_GuestGroup'),
 		);
 
+		if( isset($_SERVER['REMOTE_ADDR']) ) {
+			$fields_hash['IpAddress'] = $_SERVER['REMOTE_ADDR']; // getenv('REMOTE_ADDR') won't work on IIS, so use $_SERVER instead
+		}
+
 		parent::StoreSession($session, $fields_hash);
 	}
 
Index: kernel/utility/http_query.php
===================================================================
--- kernel/utility/http_query.php	(revision 14103)
+++ kernel/utility/http_query.php	(working copy)
@@ -105,7 +105,7 @@
 		$this->Conn =& $this->Application->GetADODBConnection();
 		$this->Order = $order;
 
-		if (array_key_exists('HTTP_X_REQUESTED_WITH', $_SERVER) && $_SERVER['HTTP_X_REQUESTED_WITH'] == 'XMLHttpRequest') {
+		if ( isset($_SERVER['HTTP_X_REQUESTED_WITH']) && $_SERVER['HTTP_X_REQUESTED_WITH'] == 'XMLHttpRequest') {
 			// when AJAX request is made from jQuery, then create ajax variable,
 			// so any logic based in it (like redirects) will not break down
 			$_GET['ajax'] = 'yes';
Index: units/helpers/curl_helper.php
===================================================================
--- units/helpers/curl_helper.php	(revision 14103)
+++ units/helpers/curl_helper.php	(working copy)
@@ -132,13 +132,16 @@
 				// hardcoded options
 				CURLOPT_RETURNTRANSFER => 1,
 				CURLOPT_REFERER => PROTOCOL.SERVER_NAME,
-				CURLOPT_USERAGENT => $_SERVER['HTTP_USER_AGENT'],
-				
+
 				// don't verify SSL certificates
 				CURLOPT_SSL_VERIFYPEER => false,
 				CURLOPT_HTTPHEADER => Array ('Expect:'),
 			);
 
+			if ( isset($_SERVER['HTTP_USER_AGENT']) ) {
+				$default_options[CURLOPT_USERAGENT] = $_SERVER['HTTP_USER_AGENT'];
+			}
+
 			if ($this->requestHeaders) {
 				$default_options[CURLOPT_HTTPHEADER] = $this->prepareHeaders();
 			}