diff --git a/reactos/subsys/csrss/api/process.c b/reactos/subsys/csrss/api/process.c
index 75c5596cde1..48fd6c3c995 100644
--- a/reactos/subsys/csrss/api/process.c
+++ b/reactos/subsys/csrss/api/process.c
@@ -1,4 +1,4 @@
-/* $Id: process.c,v 1.33 2004/04/09 20:03:15 navaraf Exp $
+/* $Id: process.c,v 1.34 2004/06/27 10:16:59 weiden Exp $
  *
  * reactos/subsys/csrss/api/process.c
  *
@@ -411,6 +411,11 @@ CSR_API(CsrDuplicateHandle)
   Reply->Header.DataSize = sizeof(CSRSS_API_REPLY) - LPC_MESSAGE_BASE_SIZE;
 
   ProcessData = CsrGetProcessData(Request->Data.DuplicateHandleRequest.ProcessId);
+  if (ProcessData == NULL)
+    {
+      DPRINT1("CsrGetProcessData() failed for process 0x%x, unable to dublicate handle\n", Request->Data.DuplicateHandleRequest.ProcessId);
+      return STATUS_INVALID_HANDLE;
+    }
   Reply->Status = CsrGetObject(ProcessData, Request->Data.DuplicateHandleRequest.Handle, &Object);
   if (! NT_SUCCESS(Reply->Status))
     {
diff --git a/reactos/subsys/csrss/api/wapi.c b/reactos/subsys/csrss/api/wapi.c
index 00a2a76514f..15d7ba00eae 100644
--- a/reactos/subsys/csrss/api/wapi.c
+++ b/reactos/subsys/csrss/api/wapi.c
@@ -1,4 +1,4 @@
-/* $Id: wapi.c,v 1.34 2004/04/09 20:03:15 navaraf Exp $
+/* $Id: wapi.c,v 1.35 2004/06/27 10:16:59 weiden Exp $
  * 
  * reactos/subsys/csrss/api/wapi.c
  *
@@ -135,7 +135,12 @@ Thread_Api2(HANDLE ServerPort)
       Reply = (PCSRSS_API_REPLY)&LpcReply;
 	
       ProcessData = CsrGetProcessData((ULONG)LpcRequest.Header.ClientId.UniqueProcess);
-
+      if (ProcessData == NULL)
+	{
+          DPRINT1("CSR: Unable to find process data for process 0x%x\n", (ULONG)LpcRequest.Header.ClientId.UniqueProcess);
+          NtClose(ServerPort);
+          continue;
+        }
       CsrApiCallHandler(ProcessData, Request, Reply);
     }
 }
@@ -182,6 +187,12 @@ void Thread_Api(PVOID PortHandle)
 	  }
 
 	ProcessData = CsrGetProcessData((ULONG)Request.Header.ClientId.UniqueProcess);
+	if (ProcessData == NULL)
+	  {
+	    DPRINT1("CSR: Unable to find process data for process 0x%x\n", (ULONG)Request.Header.ClientId.UniqueProcess);
+	    NtClose(ServerPort);
+	    continue;
+	  }
 	ProcessData->CsrSectionViewBase = LpcRead.ViewBase;
 	ProcessData->CsrSectionViewSize = LpcRead.ViewSize;