After installation of Oracle10g, there was a problem. Couldn’t login using SQL+. None of the accounts (scott/tiger) worked. At last a quick web search gave the solution. Here is what it is:

From your command prompt, type
sqlplus "/ as sysdba"

Once logged in as SYSDBA, you need to unlock the SCOTT account
SQL> alter user scott account unlock;
SQL> grant connect, resource to scott;

Now you can use scott and tiger as the username and password