Index: trunk/autoquest-htmlmonitor/src/main/java/de/ugoe/cs/autoquest/htmlmonitor/HtmlMonitorOutputWriter.java
===================================================================
--- trunk/autoquest-htmlmonitor/src/main/java/de/ugoe/cs/autoquest/htmlmonitor/HtmlMonitorOutputWriter.java	(revision 2232)
+++ trunk/autoquest-htmlmonitor/src/main/java/de/ugoe/cs/autoquest/htmlmonitor/HtmlMonitorOutputWriter.java	(revision 2233)
@@ -537,6 +537,10 @@
         if (oldLogDir.exists() && oldLogDir.isDirectory() && (oldLogDir.listFiles() != null)) {
             boolean allFilesRenamed = true;
-            for (File oldLogFile : oldLogDir.listFiles()) {
-                allFilesRenamed &= oldLogFile.renameTo(new File(newLogDir, oldLogFile.getName()));
+            File[] children = oldLogDir.listFiles();
+            
+            if (children != null) {
+            	for (File oldLogFile : children) {
+            		allFilesRenamed &= oldLogFile.renameTo(new File(newLogDir, oldLogFile.getName()));
+            	}
             }