TS-H552B Help Needed Please

Hello,

I have a Samsung TS-H552B dvd burner that has been giving me problems. When I use it to burn a disk it will burn the first disc fine, but occasionally I will here loud noises like grinding near the end of the burn (not always though). Then after I burn a disc the next disc I put in, blank or otherwise, will not be accessible. On the front of the burner the light indicating it is working stays on constantly until I reboot. I have upgraded the firmware to TS12 and for awhile the problem was fixed but it has returned. Anyone know what is happening?

Thanks,
Nick

Does anyone know why this happens?