I am getting these errors every(Daily 5 to 10 times ) now and then .The orders table ,I am calling from another database through a DB link FM.DVT .After 5 mins everything works normal .

SQL> select orderno FROM ORDERS where rownum <2;
select orderno FROM ORDERS where rownum <2
*
ERROR at line 1:
ORA-12570: TNSacket reader failure
ORA-02063: preceding line from FM.DVT


SQL> select orderno FROM ORDERS where rownum <2;
select orderno FROM ORDERS where rownum <2
*
ERROR at line 1:
ORA-02051: another session in same transaction failed
ORA-02063: preceding line from FM.DVT