Oracle Database Discussions

i have oracle 10g Database running HP-UX

i am continuosly getting the following error

**Failed - ORA-01034: ORACLE not available**
**ORA-27101: shared memory realm does not exist**
**HP-UX Error: 2: No such file or directory**

we have performed the following steps as solution

1.set $ORACLE_SID
2.set $ORACLE_SID
3.check the tnsnames.ora files permissions and restated the listener..
4.also set the registry setting parameter on Windows client machine shared_socket=true

still this error coming again and again after 10 -15 min intervals

if anyone know the exact solution for this
let me know please!!




Thanks and regards
misin