Phone Receive calls (rings) for a few hours then stops


Here’s the general problem: My phone rings for a few hours then it stops; other users attempt to dial my extension and it does not ring. If I reboot my phone, it again works, but will stop ringing. My particular setup is

System Description:
Polycom SoundPoint IP
Server Running CentOS
PBX in a Flash: 1.4

My particular setup is 2 phones sharing the same extension. The phones are setup using ServerType TrivialFTP. In the /tftpboot/ is a configuration macid.cfg file for each of the 2 phones and they point to the phone.cfg file.

Any ideas? Or if you need more info, please let me know.