ORA-01033: Oracle initialization or shutdown in progress

Hello, precursors, i am newbie in Oracle.

I've played with Oracle 8i for a short period. Everything went smoothly until yesterday i encountered a crucial problem:
ORA-01033: Oracle initialization or shutdown in progress

I tried to do following steps in SQLPLUS(as DBA):
=====================================================================
shutdown abort//startup//shutdown//startup
ORACLE instance shut down.
ORACLE instance started.

Total System Global Area   25217052 bytes
Fixed Size                    75804 bytes
Variable Size               8286208 bytes
Database Buffers           16777216 bytes
Redo Buffers                  77824 bytes
Database mounted.
ORA-01110: data file 19: 'C:\ORACLE\DBS\ORADATA\SIMONDB\OEM_REPOSITORY.ORA'
ORA-01115: IO error reading block from file 19 (block # 1)
ORA-27070: skgfdisp: async read/write failed
OSD-04016: Error queuing an asynchronous I/O request.
O/S-Error: (OS 23) Data error (cyclic redundancy check).


ORA-01109: database not open


Database dismounted.
ORACLE instance shut down.
ORACLE instance started.

Total System Global Area   25217052 bytes
Fixed Size                    75804 bytes
Variable Size               8286208 bytes
Database Buffers           16777216 bytes
Redo Buffers                  77824 bytes
Database mounted.
ORA-01110: data file 19: 'C:\ORACLE\DBS\ORADATA\SIMONDB\OEM_REPOSITORY.ORA'
ORA-01115: IO error reading block from file 19 (block # 1)
ORA-27070: skgfdisp: async read/write failed
OSD-04016: Error queuing an asynchronous I/O request.
O/S-Error: (OS 23) Data error (cyclic redundancy check).
======================================================================
It seems that OEM_REPOSITORY.ORA was corrupt and i cannot start OMS.
but OracleServiceSimondb(my database) was still running and the previously scheduled JOBs were still running!!! After that i recreated another repository before i could start OMS again.

My questions are:
1, Is there any solutions to reenter the database(because i have important data inside)?
2, If the corruption was resulted from a physical failure of HardDrive(because my harddrive "gasp"  everytime when i attempt to login or check the OEM_REPOSITORY.ORA), is there remedy?
3, How to kill the previously scheduled JOBs without drop the database?

thanks a million

BACKUP, BACKUP, BACKUP, BACKUP, BACKUP

In fact, if you have crutial data, you need to ensure
1) the best & fault-tolerant hardware to avoid any I/O errors
2) use the db_block_checksum and db_block_checking database parameters to protect even more
3) backup the database regulary, and even have the database in Archivelog mode so you can restore up to any point in time.

Regarding your questions:
1) Only if you can restore the database (see above), or if you can alter the database to remove this OEM data file.
2) see above
3) DBMS_JOB package should help you to do this job also

CHeers