Reports are scattered about the internet concerning a Windows Phone bug that is sent via text message that will reboot your Windows Phone and disable your Messaging Hub. The SMS bug is not device specific and the only solution that is available so far is a hard reset.
To make matters worse, if you've pinned a friend to your Start Screen and they get the message via Facebook, when the live tile updates to display the message, the reboot is initiated.
Nothing official from Microsoft on this kink in the system. We don't know the message sequence (and don't really want to know) but according to @ryanlowdermilk, host of Windows Phone Dev Podcast, it requires "A LOT of characters" and not something easily figured out. Still the risk is there and we wanted to let you know and if you find your Messaging Hub crashing, this may be your problem. As best we can tell, this bug doesn't expose what is on your Windows Phone but instead just makes life a little inconvenient with the hard reset.
Hopefully Microsoft can develop and distribute a software patch to fix this bug soon.