Was it happening on the default messaging app? I really don't mind switching to a different app if it fixes the problem but from what I can gather from this thread, that once it happens, it seems to happen on all messaging apps. Plus I'd like to keep my message history if possible so I have feeling I backup and restore messages the problem will keep occurring along with the new messaging app. I can't believe it's been this long and no one has found a fix for it yet. This seems like a such a big flaw in an otherwise awesome OS. I'm scared to send an MMS to any of my other contact in case it causes another split thread.