ORA-07445: exception encountered: core dump

Hi,
The error is: ORA-07445: exception encountered: core dump [ACCESS_VIOLATION]
I am getting this error in alert log while trying to open one of our oracle production db running on windows server.
I am able to mount it without any problem but once I try to open it, it just hangs and the smon trace file grows very big 500mb+ until I terminate the session.
I want to know the reasons of this error and how can I solve it?
Thanks.
