About a week ago, when I'd open up the menu listing all of my text threads with various people, I noticed a red triangle/exclamation point icon showing up next to the name of one person. A few days ago, I began experiencing trouble opening up this particular thread; I would just get the "loading" message. My friend has been able to send me texts, I just can't open them. Any idea what this might be and why it seems to be affecting only one text thread? Thanks!!