Usually, this is a cable box issue. If this happens again, turn off the cable/sat box rather than the television, and see if the sound comes back in. If it does, it's likely the HDCP (copy protection) chip in the cable box.
Many times, this can be resolved by calling the cable/sat company and having the box refreshed, reset or updated - and this can usually be initiated by them over the phone.
Sound cuts out randomly for about a second and then returns.
Occasionally it will go out and not return until we turn the TV off and back on. Or we go to the menu, sound, SRS TruSurround XT, then on or off to get the sound to come back. The TV is hooked up to a cable box with an HDMI cable. I read some other forums with similar problems. Is this an ongoing Samsung problem? Any suggestions will be appreciated.