Thread: shutting off creates text msg problem

I've had this phone since April 2008. And it's kept all my txt msgs since then, inbox and sent msgs. I go to my system info and it says I have 5 MB left. The problem I'm having is, when I switch off my phone (which is only when necessary), it deletes all my inbox and sent msgs until October 5th 2009. Does it not have enough memory to keep them while shutting down? The other problem is, I left my phone overnight to delete all sent msgs (charging), and received a msg this morning but couldn't access my inbox at all so i had to do a reset and when it turned back on i didn't have a new msg anymore and back to October 5th msgs. Please help, what can I do to fix this?