What kind of "restore" did you do? If it was just a "system restore", it would not have repaired damage to Opera program files or to any Opera files under a user account... "system restore" only restores critical system files (like the registry, critical windows files, drivers, etc). The only "true" way to restore a system to a month-earlier state would be via using an image's or file-backup's restoration program.
If you did only perform a "system restore", then a corruption or miss-adjustment problem within the Opera files themselves might still be present.