Why am I receiving a memory full notification?

Memory full warning notifications are shown once the SMS memory reaches 80% full, which is 80 out of 100 SMS.
The notifications show up every time on receiving a new message. On reaching 100%, "
Memory full notification" message is shown and no new messages will be received until we make space for incoming messages by deleting some from the inbox.
Memory full warning notices are shown only if "
Auto Erase Inbox" is set to
Off in Messaging settings (
Menu ->
Settings ->
Messaging).
If set to
On, then these notices are not shown. By default this is set to
Off.
Is there any way of getting a '1 text message recieved' box when you get a messgae and not just a tiny envelope on the top of the screen?
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