Hi inkswitch. Welcome to Android Forums. I'm not familiar with your phone and not certain what you are wanting to do. If it's a simple delete, you should be able to long press the message and a option box will appear with a delete option. I hope this helps. I'm sure another member here that owns your phone will have a more precise answer for you. I hope you enjoy your time on these forums.
You have to go into your sms chats and look for a message with a red triangle and delete that message (press / hold on that specific message and drop down box appears), if you have long chat logs, the easiest would be to completely delete the chat conversation. IIRC around 5 or 6 of these triggers this error, so I don't ever let any go un-deleted when sending messages that fail.
