Index: typo3/mod/tools/em/class.em_index.php
===================================================================
--- typo3/mod/tools/em/class.em_index.php	(revision 6130)
+++ typo3/mod/tools/em/class.em_index.php	(working copy)
@@ -1299,6 +1299,9 @@
 				'" onclick="document.location.href=\'' . t3lib_div::linkThisScript(array('l10n'=>'update')) .
 				'\'" />';
 
+				// as this page loads dynamically, quit output buffering caused by ob_gzhandler
+			$this->quitOutputBuffering();
+
 			if(t3lib_div::_GET('l10n') == 'check') {
 				$loadedExtensions = array_keys($TYPO3_LOADED_EXT);
 				$loadedExtensions = array_diff($loadedExtensions,array('_CACHEFILE'));
@@ -1309,11 +1312,10 @@
 				$content = $this->doc->startPage('Extension Manager');
 				$content.= $this->doc->moduleBody($this->pageinfo, $docHeaderButtons, $markers);
 				$contentParts=explode('###CONTENT###',$content);
-				ob_end_flush();
+
 				echo $contentParts[0].$this->content;
 
 				$this->doPrintContent = FALSE;
-				flush();
 
 				echo '
 				<br />
@@ -1404,11 +1406,10 @@
 				$content = $this->doc->startPage('Extension Manager');
 				$content.= $this->doc->moduleBody($this->pageinfo, $docHeaderButtons, $markers);
 				$contentParts=explode('###CONTENT###',$content);
-				ob_end_flush();
+
 				echo $contentParts[0].$this->content;
 
 				$this->doPrintContent = FALSE;
-				flush();
 
 				echo ('
 				<br />
@@ -6157,7 +6158,20 @@
 
 		return $content . '</table><br />';
 	}
+	
+	/**
+	 *  Quit output buffering started by ob_gzhandler (if $TYPO3_CONF_VARS[BE][compressionLevel] was set)
+	 *
+	 *  @return	void
+	 */
+	private function quitOutputBuffering() {
 
+		while (ob_get_level()) {
+			ob_end_clean();
+		}
+
+		header('Content-Encoding: None', TRUE);
+	}
 }