Index: /trunk/src/org/openstreetmap/josm/gui/SplashScreen.java
===================================================================
--- /trunk/src/org/openstreetmap/josm/gui/SplashScreen.java	(revision 12404)
+++ /trunk/src/org/openstreetmap/josm/gui/SplashScreen.java	(revision 12405)
@@ -161,5 +161,8 @@
                 throw new IllegalStateException("This task has already been finished: " + name);
             }
-            duration = tr(" ({0})", Utils.getDurationString(System.currentTimeMillis() - start));
+            long time = System.currentTimeMillis() - start;
+            if (time >= 0) {
+                duration = tr(" ({0})", Utils.getDurationString(time));
+            }
         }