iPhone 4s message ringtone won't stop...

[bbchick]

Whenever my 4s receives two text messages at the same time my ringtone won't stop unless I turn off the phone! It won't stop when I open the message. It won't lower the volume or mute the ring even when I press the appropriate buttons. The phone is just stuck on the ringtone until I power off the phone! Anybody else experienced this? How can I fix it?

Thanks.

 

[bbchick]

Anybody else has this problem?

If you've received two texts at the same time and has NEVER encountered this "endless" ringtone problem please let me know also.

Thanks.