I installed a fresh copy of Oracle Enterprise Edition 8.1.7 on Windows 2003. After the install when I log in to svrmgr... or SQL*Plus, I get the following error: ORA-12560: TNS: protocol adapter error. And I can't connect as internal to create database. Could you please help solve this problem?
First, you should know that "connect internal" and the svrmgrl tool were both deprecated as of 8.1.5. However, Oracle still allowed the functionality until 9.0. So, what you're trying to do should work until 9.0.
The problem you're describing is something I've seen and, for me, it usually has to do with a setting in the sqlnet.ora file. I would try adding (if it isn't there) or removing (if it is there) a line like this:
You may also try logging out and logging back in as the user that you used to install Oracle. This is because during the installation, Oracle creates a new local group named ORA_DBA and adds you to that group. Membership in that group is what determines who is allowed to use functionality like "connect / as sysdba" (a.k.a. "connect internal"). If you're in the group ORA_DBA, you can use the "connect / as sysdba" and if you aren't then you get an insufficient privileges error.