Permission denied starting up on Windows

I'm having trouble getting Oracle 8.1 installed and running on Windows 2000 Server. The listener service (as well as other services) fail to start. I get a variety of error messages, but they all seem to have an "Error 5, Permission Denied" somewhere in them.

I'm running as Administrator so I'm puzzled as to what permission I need that I don't have. Examples of the error messages are below. My system specs, etc. are:

 Windows 2000 Server (5.00.2195)
 Service Pack 2

 The Oracle Home directory is on a mapped drive.

Any help would be appreciated.

Dave

The error messages:

In Services, clicking on 'Start' for OracleOraHome81TNSListener results in a message box with:
 Could not start the OracleOraHome81TNSListenerservice on Local Computer.  Error 5: Access is denied.

Clicking on 'Start' for OracleOraHome81Agent results in a message box with:  Could not start the OracleOraHome81Agent service on Local Computer.  Error 5: Access is denied.

The same happens if I try from the command line.

LSNRCTL> start
Starting tnslsnr: please wait...

Failed to open service <OracleOraHome81TNSListener>, error 1060. Failed to start service, error 5.
TNS-12536: TNS:operation would block
 TNS-12560: TNS:protocol adapter error
  TNS-00506: Operation would block
   32-bit Windows Error: 997: Unknown error Received on Fri Nov 22 2002 - 09:41:09 CST