Oracle Database Discussions

Suddenly my database started having this issue :

I set ORACLE_SID=Build
sqlplus /nolog
connect sys/dba as sysdba
Connected to an idle instance.
startup

I get the error
ORA-27100: shared memory realm already exists
and so I run
shutdown

I get the error
ORA-27101: shared memory realm does not exist

I delete and recreated the instance, I deleted the password file and recreated the password file.. but the problem still exists. I rebooted the machine but I am not able to start the database. I am not able to connect to the database.

Database Verion : 10.1.0.2.0
Windows Version : Microsoft Windows Server 2003 Advanced Server

There are not errors or any trace files. Alert log just shows this :
Thu May 27 10:33:35 2004
ORACLE V10.1.0.2.0 - Production vsnsta=0
vsnsql=13 vsnxtr=3
Windows Server 2003 Version V5.2
CPU : 1 - type 586, 1 Physical Cores
Process Affinity: 0x00000000
Memory (A/P) : PH:2582M/3069M, PG:4637M/4964M, VA:1959M/2047M
Thu May 27 10:33:35 2004
Starting ORACLE instance (normal)
Thu May 27 10:34:43 2004
Starting ORACLE instance (normal)

Any help in this is greatly appreciated.

-Nags