I bought a SC-HT900 couple years ago and not long after having it, video began to (if I remember correctly) freeze up when playing movies. I did some research and found out it is the decoder chip overheating. There are no fans or top ventilation in the disc player (SA-HT900) (although there is some vents on the bottom, lol what?). So I cut a hole in the top (this was a chore) above the decoder chip, which is on the green circuit board and says DTS, and put a 12 volt fan on it. Looked for a place on the circuit board providing the proper voltage and connected the negative to a screw for ground. The location to solder the positive wire to is (going by this picture I forgot to write it down) J328. There is C750 above that towards the back. The bottom of this picture is facing the front.
It is pretty quiet. I’ve been using it for years now, maybe a couple times a month without problems. There is supposedly another issue with a fan in the subwoofer that causes popping noises in the speakers. But I haven’t had this problem. I could probably fix it the same way. Here is how one person fixed it.
I doubt this is going to be of help to anyone since this system is so old, but I thought I would share. You never know.
Here is some detailed troubleshooting information about a freezing issue.