Could not start the TNSListener service on Local Computer

I installed Oracle 10g rel 2 under Windows 2000. The computer is DHCP, so I installed the MS loop adapter, and am able to successfully the new IP address.

SQL*Plus returns this error:

ORA-12541: TNS:no listener

When I try to start the listener via control panel > services, I get this Microsoft Management Console error:

Could not start the OracleOraDb10g_home1TNSListener service on Local Computer. The service did not return an error. This could be an internal Windows error or an internal service error. If the problem persists, contact your system administrator.

My full computer name (via control panel) is dimension4100.ora.newmiddleclass.com and it is a member of workgroup WORKGROUP.

C:\WINNT\system32\drivers\etc\hosts contains (I added the 2nd line):

127.0.0.1 localhost
192.168.255.255 dimension4100.ora.newmiddleclass.com dimension4100

# listener.ora Network Configuration File: C:\oracle\product\10.2.0\db_1\network\admin\listener.ora
# Generated by Oracle configuration tools.

SID_LIST_LISTENER =
(SID_LIST =
(SID_DESC =
(SID_NAME = PLSExtProc)
(ORACLE_HOME = C:\oracle\product\10.2.0\db_1)
(PROGRAM = extproc)
)
)

LISTENER =
(DESCRIPTION_LIST =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1))
(ADDRESS = (PROTOCOL = TCP)(HOST = ora.newmiddleclass.com)(PORT = 1521))
)
)

# tnsnames.ora Network Configuration File: C:\oracle\product\10.2.0\db_1\network\admin\tnsnames.ora
# Generated by Oracle configuration tools.

HCM =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = ora.newmiddleclass.com)(PORT = 1521))
(CONNECT_DATA =
(SERVER = DEDICATED)
(SERVICE_NAME = HCM.ora.newmiddleclass.com)
)
)

EXTPROC_CONNECTION_DATA =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1))
)
(CONNECT_DATA =
(SID = PLSExtProc)
(PRESENTATION = RO)
)
)

My SID is HCM.

Can someone please suggest a solution? Thanks.