Just recently had to do a factory reset on my phone (was in a constant loop of turning on and turning off), and ever since the reset, I have not been able to send text messages to one of my contacts.
If I compose a new message and select the contact from the list then I can send them fine, and as long as I keep that thread open I can send texts. However when I close the thread, I notice that, in my list of text messages to contacts, this one particular contact reverts from the name of the contact to simply his number with a '*' beside it. When I go back into the thread to send him more texts they all fail to send.
Galaxy S Vibrant from Bell