the event I had to set in the init file is:
event="10061 trace name context forever, level 10"

Sambavan,
Yes I had set the SID correctly, now after setting the event I had no problem in starting up. But the problem now is I have started getting ora 600 errors again in user trace files:
ksedmp: internal or fatal error
ORA-00600: internal error code, arguments: [25012], [4], [3], [], [], [], [], []
No current SQL statement being executed.
----- Call Stack Trace -----
calling call entry argument values in hex
location type point (? means dubious value)
-------------------- -------- -------------------- ----------------------------
_ksedmp+a8 CALLrel _ksedst+0
2FCCF7C
_ksfdmp+e CALLrel _ksedmp+0 3
_kgeriv+95 CALLreg 00000000
A5158
3
_kgesiv+49 CALLrel _kgeriv+0
C54B8
23044654
61B4
2
22FCD0FC
_ksesic2+3c CALLrel _kgesiv+0
A5158
23044654
61B4
2
22FCD0FC
_kftr2ah+f7 CALLrel _ksesic2+0 61B4
0 4 0
3
_kcblrs+ed CALLrel _kftr2ah+0
_kcblrd+43 CALLrel _kcblrs+0
A4FD0
_kcblgt+17e CALLrel _kcblrd+0
_kcbldrget+73 CALLrel _kcblgt+0
304C6D0
4
C1E8B5
_kcbgtcr+ac CALLrel _kcbldrget+0
309B55C
0
_kdlrdb+94 CALLrel _kcbgtcr+0
_kdlprl+158 CALLrel _kdlrdb+0
2FCDD54
22FCDA88
22FCDC0C
0
22FCDF3C
B3CC10
0
1FC4
_kdl_read+587 CALLrel _kdlprl+0
2FCDD54
22FCDC0C
C1E8B5
2 0 0
22FCDF3C
B3CC10
0
3869
22FCDA88
22FCDAFC
_koklread+366 CALLrel _kdl_read+0
2FCDD54
22FCDE44
0
22FCDD14
0
22FCDF3C
B3CC10
22FCDD10
_kpolob+1f5 CALLrel _koklread+0
2FCE4D0
0 0 1
22FCE4C8
0 0
22FCDF3C
B3CC10
0 0
_opiodr+507 CALLreg 00000000 60 C
22FCEF80
_ttcpip+df8 CALLreg 00000000 60 C
22FCEF80
0
_opitsk+608 CALLrel _ttcpip+0
_opiino+50c CALLrel _opitsk+0 0
_opiodr+507 CALLreg 00000000 3C 4
22FCFBF8
_opidrv+384 CALLrel _opiodr+0 3C 4
22FCFBF8
0
_sou2o+19 CALLrel _opidrv+0
_opimai+10c CALLrel _sou2o+0
_OracleThreadStart@4+4b8 CALLrel _opimai+0 2
22FCFE74
77E87587 CALLreg 00000000

I am waiting for response from metalink.

Thanx,
Kavita