Unable to connect the database from sqlplus.

When we try to connect the database through the sqlplus from the client machine (Windows Vista) installed with oracle 10g client . It trys to connect the database and the sql window disappears without any error message.

If you type the sqlplus on the command prompt you will receive the following error message.

SP2-1503: Unable to initialize Oracle call interface
SP2-0152: ORACLE may not be functioning properly.

This issue can be resolved as shown below.

Goto start  Control panel  User accounts  Turn User Account Control On or Off 
Uncheck the below option.

Use User Account Control(UAC) to help protect your computer.

Restart the machine and try to connect. It works fine