This is shitty . I dont know if its a bug but try this . Open Orkut in new window and delete your account with the first window . Though Google shows account deleted but you are still able to access orkut with the other window without any display error .
It takes some time before the account is deleted..sometimes 2-3 days. If you "delete your account" and access it again before the system actually deletes it, it won't get deleted.