Fixed a typo. According to the url pointed out by Royce3, it's right ( http://www.osronline.com/lists_archive/ntdev/thread1866.html)

Modified: trunk/reactos/ntoskrnl/ke/event.c

--- trunk/reactos/ntoskrnl/ke/event.c	2005-08-10 11:45:50 UTC (rev 17257)
+++ trunk/reactos/ntoskrnl/ke/event.c	2005-08-10 16:33:49 UTC (rev 17258)
@@ -44,7 +44,7 @@

     /* Initialize the Dispatcher Header */
     KeInitializeDispatcherHeader(&Event->Header,
                                  Type,

-                                 sizeof(Event) / sizeof(ULONG),

+                                 sizeof(*Event) / sizeof(ULONG),

                                  State);
 }