Incredible memory issue

Does anyone know about an issue with the Incredible stating that the sms memory is low or phone memory is low? My friends phone is saying this and he can't send any messages or do to much on his phone because of this but he still has plenty of memory when looking at it in the settings. Any thoughts?

 

I ran into this problem a few weeks ago, in searching the forums and google in general, the only real solution was to do a factory reset, the consensus seems to be that the native mail app is the cause of this. I reset and started using K9 mail, and havn't had any issues.

 

cool thanks