HT-S580 Randomly Shuts-Off

Most systems like this have what is commonly called 'protect' mode. This usually kicks in when the volume is at a very high level, and the unit tries to use more power than its designed for, or it is overheating.

The reason why only this connection has problems and others do not could be a few reasons. One, satellite signals usually carry high quality digital sound, and use more power to play sounds that may be inaudible.

Two, You may also want to upgrade your composite cables to the highest possible quality. (There are many durable gold plated models that work well). Low quality cables could hasten your problem and produce signal bleed.

In addition to this, the unit may cut power when it overheats. Make sure the vents on the unit are not obstructed, and that it is not near other components that are generating heat.