The pont_string key is added only after you disable one of the dialogs.
Try this: use the conversation view (enable on the View ribbon) then select and delete a conversations (and all the messages in it). You should get a dialog telling you that you are deleting the conversation with the don't show again checkbox. Check it and click OK then look in the registry. Do you see the pont_string key now?
If you don't get the dialog, then you have the pont_string key with at least the value for that dialog (it's 75 or 78, I forget exactly offhand)
(Use Ctrl+Z to undo or retrieve it from the deleted items folder.)
The dialog looks like this: