ORA-01031: insufficient privileges ON WINDOWS!

In most cases, the user receiving this error lacks a previlage to create an object (such as a table, view, procedure and the like).

Grant the required privilege like so:

grant create table to user_lacking_privilege;

Startup

If someone receives this error while trying to startup the instance, the logged on user must belong to the ora_dba group on Windows or dba group on Unix.

To add a user to the ora_dba group on Windows, net localgroup should help:

C:\> net localgroup ora_dba rene /add