SQL*Plus (unusual) problem

Hoj!

[Quoted] I have a table A with definition

[Quoted] [Quoted]  Name                            Null?    Type
 ------------------------------- -------- ----
 OPO_ID                          NOT NULL NUMBER(8)
 OPOMBA                          NOT NULL VARCHAR2(2000)
 LOK_ID                          NOT NULL VARCHAR2(5)
 REP_ID                          NOT NULL VARCHAR2(200)

Then I make in SQL*Plus simple SELECT
Exam.: SELECT * FROM TABEL_A WHERE ROWNUM < 2; and I (allways) get:
"buffer overflow. Use SET command to reduce ARRAYSIZE or increase MAXDATA."

I've tried to modify those values (ARRAYSIZE and MAXDATA), but I still get this message.
Any ideas what else could be wrong?

-- 
Boštjan Štupica