Hallo SAPGuru,
Oracle läuft (habs testweise herunter- und nochmal hochgefahren), da gibts keine Probleme. Der Listener läuft ebenfalls. Die Konfiguration des Listeners sieht wie folgt aus:
tnsnames.ora
# TNSNAMES.ORA Network Configuration File: G:\database\ora92\network\admin\tnsnames.ora
# Generated by Oracle configuration tools.
ORCL =
  (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = TCP)(HOST = powerbook)(PORT = 1521))
    )
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = ORCL)
    )
  )
INST1_HTTP =
  (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = TCP)(HOST = powerbook)(PORT = 1521))
    )
    (CONNECT_DATA =
      (SERVER = SHARED)
      (SERVICE_NAME = MODOSE)
      (PRESENTATION = http://HRService)
    )
  )
EXTPROC_CONNECTION_DATA =
  (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC0))
    )
    (CONNECT_DATA =
      (SID = PLSExtProc)
      (PRESENTATION = RO)
    )
  )
DRS.WORLD = 
  (DESCRIPTION = 
    (SDU = 32768)
    (ADDRESS_LIST = 
      (ADDRESS = 
        (COMMUNITY = SAP.WORLD)
        (PROTOCOL = TCP)
        (HOST = powerbook)
        (PORT = 1527)
      )
    )
    (CONNECT_DATA = 
      (SID = DRS)
      (GLOBAL_NAME = DRS.WORLD)
    )
  )
listener.ora
# LISTENER.ORA Network Configuration File: G:\database\ora92\network\admin\listener.ora
# Generated by Oracle configuration tools.
LISTENER =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS_LIST =
        (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC0))
      )
      (ADDRESS_LIST =
        (ADDRESS = (PROTOCOL = TCP)(HOST = powerbook)(PORT = 1521))
      )
    )
    (DESCRIPTION = 
      (ADDRESS = 
        (PROTOCOL = IPC)
        (KEY = DRS.WORLD)
      )
    )
    (DESCRIPTION = 
      (ADDRESS = 
        (PROTOCOL = IPC)
        (KEY = DRS)
      )
    )
    (DESCRIPTION = 
      (ADDRESS = 
        (COMMUNITY = SAP.WORLD)
        (PROTOCOL = TCP)
        (HOST = powerbook)
        (PORT = 1527)
      )
    )
  )
SID_LIST_LISTENER =
  (SID_LIST =
    (SID_DESC =
      (SID_NAME = PLSExtProc)
      (ORACLE_HOME = G:\database\ora92)
      (PROGRAM = extproc)
    )
    (SID_DESC =
      (GLOBAL_DBNAME = ORCL)
      (ORACLE_HOME = G:\database\ora92)
      (SID_NAME = ORCL)
    )
    (SID_DESC = 
      (SDU = 32768)
      (SID_NAME = DRS)
      (ORACLE_HOME = G:\database\ora92)
    )
  )
STARTUP_WAIT_TIME_LISTENER = 0
CONNECT_TIMEOUT_LISTENER = 10
TRACE_LEVEL_LISTENER = OFF
Mir ist aufgefallen, dass bei tnsnames,ora und listener.ora Port 1527 eingestellt ist. Kann das stimmen? r3trans -d liefert folgendes Ergebnis:
c:\>r3trans -d
This is r3trans version 6.08 (release 620 - 04.02.03 - 14:54:00).
2EETW169 no connect possible: "DBMS = ORACLE                           --- dbs_ora_tnsname = 'DRS'"
r3trans finished (0012).
Die trans.log enthält folgende Daten:
4 ETW000 r3trans version 6.08 (release 620 - 04.02.03 - 14:54:00).
4 ETW000 ===============================================
4 ETW000 
4 ETW000 date&time   : 29.05.2009 - 06:12:37
4 ETW000 control file: <no ctrlfile>
4 ETW000 R3trans was called as follows: r3trans -d
4 ETW000  trace at level 2 opened for a given file pointer
4 ETW000  [dev trc     ,00000]  Fri May 29 06:12:40 2009             0.000000
4 ETW000  [dev trc     ,00000]  db_con_init called                   0.000000
4 ETW000  [dev trc     ,00000]  create_con (con_name=R/3)            0.000000
4 ETW000  [dev trc     ,00000]  Loading DB library 'dboraslib.dll' ...
4 ETW000                                                             0.000000
4 ETW000  [dev trc     ,00000]  load shared library (dboraslib.dll), hdl 0
4 ETW000                                                      61272  0.061272
4 ETW000  [dev trc     ,00000]      using "G:\usr\sap\DRS\SYS\exe\run\dboraslib.dll"
4 ETW000                                                        104  0.061376
4 ETW000  [dev trc     ,00000]  Library 'dboraslib.dll' loaded
4 ETW000                                                         86  0.061462
4 ETW000  [dev trc     ,00000]  function DbSlExpFuns loaded from library dboraslib.dll
4 ETW000                                                         97  0.061559
4 ETW000  [dev trc     ,00000]  Version of 'dboraslib.dll' is "620.02", patchlevel (0.549)
4 ETW000                                                        354  0.061913
4 ETW000  [dev trc     ,00000]  function dsql_db_init loaded from library dboraslib.dll
4 ETW000                                                         95  0.062008
4 ETW000  [dev trc     ,00000]  function dbdd_exp_funs loaded from library dboraslib.dll
4 ETW000                                                        145  0.062153
4 ETW000  [dev trc     ,00000]  New connection 0 created        103  0.062256
4 ETW000  [dev trc     ,00000]  0: name = R/3, con_id = -000000001 state = DISCONNECTED, perm = YES, reco = NO
4 ETW000                                                        103  0.062359
4 ETW000  [dev trc     ,00000]  db_con_connect (con_name=R/3)
4 ETW000                                                         84  0.062443
4 ETW000  [dev trc     ,00000]  find_con found the following connection for reuse:
4 ETW000                                                         86  0.062529
4 ETW000  [dev trc     ,00000]  0: name = R/3, con_id = 000000000 state = DISCONNECTED, perm = YES, reco = NO
4 ETW000                                                         94  0.062623
4 ETW000  [dev trc     ,00000]  Got ORACLE_HOME=G:\database\ora92 from environment
4 ETW000                                                        730  0.063353
4 ETW000  [dev trc     ,00000]  -->oci_initialize                74  0.063427
4 ETW000  [dev trc     ,00000]  Client NLS settings: AMERICAN_AMERICA.WE8DEC
4 ETW000                                                     114555  0.177982
4 ETW000  [dev trc     ,00000]  Logon as OPS$-user to get SAPDRS's password
4 ETW000                                                        329  0.178311
4 ETW000  [dev trc     ,00000]  Connecting as /@DRS on connection 0 ...
4 ETW000                                                         89  0.178400
4 ETW000  [dev trc     ,00000]  Allocating service context handle
4 ETW000                                                        118  0.178518
4 ETW000  [dev trc     ,00000]  Allocating server context handle
4 ETW000                                                        121  0.178639
4 ETW000  [dev trc     ,00000]  Attaching to DB Server DRS (con_hdl=0,svchp=0022D4D4,svrhp=01783DB4)
4 ETW000                                                        187  0.178826
4 ETW000  [dev trc     ,00000]  Assigning server context 01783DB4 to service context 0022D4D4
4 ETW000                                                     375426  0.554252
4 ETW000  [dev trc     ,00000]  Allocating user session handle
4 ETW000                                                       4584  0.558836
4 ETW000  [dev trc     ,00000]  Starting user session (con_hdl=0,svchp=0022D4D4,srvhp=01783DB4,usrhp=0178C54C)
4 ETW000                                                        322  0.559158
4 ETW000  [dboci.c     ,00000]  *** ERROR => OCI-call 'OCISessionBegin' failed: rc = 1033
4 ETW000                                                      39662  0.598820
4 ETW000  [dboci.c     ,00000]  *** ERROR => CONNECT failed with sql error '1033'
4 ETW000                                                         62  0.598882
4 ETW000  [dev trc     ,00000]  Try to connect with default password
4 ETW000                                                         73  0.598955
4 ETW000  [dev trc     ,00000]  Connecting as SAPDRS/<pwd>@DRS on connection 0 ...
4 ETW000                                                         51  0.599006
4 ETW000  [dev trc     ,00000]  Assigning username to user session 0178C54C
4 ETW000                                                         48  0.599054
4 ETW000  [dev trc     ,00000]  Assigning password to user session 0178C54C
4 ETW000                                                         73  0.599127
4 ETW000  [dev trc     ,00000]  Starting user session (con_hdl=0,svchp=0022D4D4,srvhp=01783DB4,usrhp=0178C54C)
4 ETW000                                                         53  0.599180
4 ETW000  [dboci.c     ,00000]  *** ERROR => OCI-call 'OCISessionBegin' failed: rc = 1033
4 ETW000                                                      13787  0.612967
4 ETW000  [dboci.c     ,00000]  *** ERROR => CONNECT failed with sql error '1033'
4 ETW000                                                         63  0.613030
4 ETW000  [dblink      ,00419]  ***LOG BY2=>sql error 1033   performing CON [dblink#1 @ 419]
4 ETW000                                                        154  0.613184
4 ETW000  [dblink      ,00419]  ***LOG BY0=>ORA-01033: ORACLE initialization or shutdown in progress [dblink#1 @ 419]
4 ETW000                                                         55  0.613239
2EETW169 no connect possible: "DBMS = ORACLE                           --- dbs_ora_tnsname = 'DRS'"
tnsping DRS liefert folgendes Ergebnis:
c:\>tnsping DRS
TNS Ping Utility for 32-bit Windows: Version 9.2.0.2.0 - Production on 29-MAY-20
09 06:25:08
Copyright (c) 1997 Oracle Corporation.  All rights reserved.
Used parameter files:
G:\database\ora92\network\admin\sqlnet.ora
Used TNSNAMES adapter to resolve the alias
Attempting to contact (DESCRIPTION = (SDU = 32768) (ADDRESS_LIST = (ADDRESS = (C
OMMUNITY = SAP.WORLD) (PROTOCOL = TCP) (HOST = powerbook) (PORT = 1527))) (CONNE
CT_DATA = (SID = DRS) (GLOBAL_NAME = DRS.WORLD)))
OK (10 msec)
In der Hosts sind m.E. alle erforderlichen Einträge enthalten:
127.0.0.1       localhost
192.168.12.1 powerbook
Kannst du dir aufgrund der oben gezeigten Files einen Reim auf den Fehler machen? 
Liebe Grüße,
Azrael