Below are some ORA-ERROR which every DBA face:
Clause: Most likely it is related to bug
Solution: go to metalink and apply patch set.
Clause: It is generic error means lots of reason behind this.
Solution: Depends on condition but best way to search on google/forms.
Clause: Mis-configuration of SGA, insufficient memory
Solution: Sametime need to add memory on system, or sametime need to reduce SGA memory