Sanyo MM-8300

Has anyone had this happen? If I attempt to go into my contact list, the phone freezes. I have to take the battery out and put it back just to get the phone to turn on again. This also happens when using the when using Text Messages. I can receive, read, but not reply because the phone freezes. I also see this when using the Camera.

I have taken the phone to Sprint and they were unable to fix, as they don't know what the problem is. I was just curious if anyone else has seen this.

Thanks!
TRM