All of the messages in my "Messages" application are being deleted without me deleting them. Every once in a while, I'll check, and all the messages will be gone.

I checked all the options and there doesn't seem to be anything that could be the source of this problem.

Any suggestions?

check your available memory.. BB automatically deletes sms, mms, emails and such if you are running low on your free memory.

Try this
http://www.blackberryforums.com/gene...ee-memory.html