Oracle Database Express Edition (XE)

Hello,

i'm trying to run an external c procedure in xe on windows server 2008.
The procedure is created like described in Steven Feuersteins book Oracle PL/SQL Programming.

When i try to run my procedure it results in an ORA-28575. The listener log also states TNS-12518 and TNS-12560.

Here are my tnsnames.ora

XE =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = manzano108)(PORT = 1521))
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = XE)
    )
  )

EXTPROC_CONNECTION_DATA =
  (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC_FOR_XE))
    )
    (CONNECT_DATA =
      (SID = PLSExtProc)
      (PRESENTATION = RO)
    )
  )

ORACLR_CONNECTION_DATA = 
  (DESCRIPTION = 
    (ADDRESS_LIST = 
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC_FOR_XE)) 
    ) 
    (CONNECT_DATA = 
      (SID = CLRExtProc) 
      (PRESENTATION = RO) 
    ) 
  ) 

and listener.ora

SID_LIST_LISTENER =
  (SID_LIST =
    (SID_DESC =
      (SID_NAME = PLSExtProc)
      (ORACLE_HOME = C:\oraclexe\app\oracle\product\10.2.0\server\bin)
      (PROGRAM = extproc)
    )
    (SID_DESC =
      (SID_NAME = CLRExtProc)
      (ORACLE_HOME = C:\oraclexe\app\oracle\product\10.2.0\server\bin)
      (PROGRAM = extproc)
    )
  )

LISTENER =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC_FOR_XE))
      (ADDRESS = (PROTOCOL = TCP)(HOST = manzano108)(PORT = 1521))
    )
  )

DEFAULT_SERVICE_LISTENER = (XE)

I can tnsping all listeners successfull.

When i run "lsnrctl services" i get:

Service "PLSExtProc" has 1 instance(s).
  Instance "PLSExtProc", status UNKNOWN, has 1 handler(s) for this service...
    Handler(s):
      "DEDICATED" established:0 refused:3
        LOCAL SERVER

Does refused:3 mean that there are some restrictions on running the process?

On a testsystem running windows xp it works fine, when i run the procedure i can see in the task manager that extproc.exe is run, on windows 2008 server this is not the case.

Thanks for help in advance,
Dirk