How to Disable/See/Reply Visitor Messages in vB 5.1.1

[raunekk]

I get a notification in email saying "There is a new post in Forum Visitor Messages" but when I click on the link the question is not displayed and there is only one button visible i.e. Post Reply.

There are 2 things I would like to ask

1. Where do these visitors put the messages? And I had done setting such that only a registered user can start a topic. Then how are these visitors able to put messages??
2. From where do I disable this visitor message option. i.e i dont want any user to ask anything without registering to the forum. I looked in the Settings -> Options -> Visitor Messages but couldnt find any such option.

I am currently using version 5.1.1.

Pls Pls help as I get loads of visitor messages everyday.