First let me Thank you SVK.
Yes..We are in touch with oracle support...with seviority 1.

The database is huge..but we have restored in another server
and trying...all the options.

Oracle asked to not to shut down any cost...yes we did.it is up.

we tried one Dummy user to export his table we got no error..(Table has 3 rows only)...That we could not understand.

All the time database started up nicely without error.
Thanks.
Thanigaivasan.