BDE Error: 9729 Key violation.

I have installed on my computer Oracle 8.0.5 and I'm programming in Delphi
4.0. While trying to view the contents of any table from SQL Explorer it
returns the following error :

Key violation. (BDE Error: 9729)
[Oracle][ODBC][Ora]ORA-00904: invalid column name (BDE Error:13059)

May be this question was already discussed - just give me a clue.

I need desperately help!!!

Veaceslav