ORA-12560: TNS:protocol adapter error after 8i installation and new db creation

I installed Oracle 8i on Windows 2000, but the installation was stuck when configuring Net8, Database Configuration Assistant and Oracle HTTP Service (the 3 optional tools). I checked that the following 6 Oracle services were installed under Windows Services:

Service name Status Startup

OracleOraHome81Agent	    Started		Automatic
OracleOraHome81ClientCache		        Manual
OracleOraHome81DataGatherer Started	        Automatic
OracleOraHome81HTTPServer		        Manual
OracleOraHome81PagingServer		        Manual
OracleOraHome81TNSListener  Started	        Automatic

I assumed that my Oracle installation was successful. But when I tried to use SQLPlus as follows:

sqlplus /nolog
conn / as sysdba

I got the error:
ORA-12560: TNS:protocol adapter error

I haven't created any database yet. I also tried to create a database manullay using Database Configuration Assistant. After I went through all the configuration, I got the same error, and the database was not created.

Anybody has any idea what could go wrong?

Thanks,

Jianqun

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