BB Messenger conversation disappeared?

Was having a bb messenger conversation last nite, which was not that long, but I wanted to review it again this morning. I sent the last im which was delivered and read by the recipient.

When I woke, the conversation was no longer there. I did not end the conversation. The person I was having the conversation with has not deleted me as a contact as far as I'm aware (no reason to, and the contact still shows up in my contact list). It's my understanding that if the other person deletes me as a contact (which will end the conversation on both ends I believe), the contact is also instantly deleted from my bb messenger contacts list, correct?

Any ideas how this happened? Is there a way for the other party to end the conversation and clear the history on my end without deleting me as a contact (in which case their contact would be off my list).

I'm dealing with a slightly sensitive situation, but not one which I would ever think the other person would get upset and want to end the conversation or delete me from their contacts. In my contact list, the contact is still there and under contact info shows as "active".

Battery was going dead last night (green flashing light), but phone was still on and operational this morning.

What applications do you have downloaded? This was happening to a friend of mine and it was Ubertwitter. She deleted the app and BBM's conversations are ok now.

Really nothing other than what came on the blackberry. And about all I use on it is the phone, email, and bbm.