Samsung Behold, ''unsupported message!''

Yesterday I received a text message from a friend in my MyFav's plan who also has T-Mobile. I went to open the message and the Phone said ''unsupported message''. Normally I wouldnt care except I cannot get it to stop alerting me to this message being unread. Every 5 minutes my phone chimes that I have a message. When I go to that friends contact info page it shows the lil envelope indicating an unread message. Its also annoying because even when I am on the phone using another application or even sending a text it keeps vibrating to alert me of this unread message. A message I cannot read or delete. I have already changed the sound profiles so that it doesn't alert me but that hasnt changed it nor does it fix the problem only maybe a symptom. I have also turned it off and on again.

Any suggestions?? Would this be a Samsung problem or a carrier problem??