Overheating? after running for about 30 minutes, my receiver shuts down. I have other components stacked on top of it in my entertainment center and am concerned that configuration may be causing it to overheat. Is this a common problem for this receiver?

Well you have covered the main two, overheating and failing capacitors. The only other one I can think of is a component / IC dry joint on the circuit board. As the board heats up, the connection fails. Or something is failing internally when heating up.

Sounds like you are overheating. One way to tell if it's overheating is you say it will run for about 30 minutes then shuts down. When it shuts down try rebooting to see if the boots successfully. If it fails to boot successfully right after it shut down then you are probably overheating. If you wait awhile to let it cool down for 30 minutes or so and if you reboot and it does it successfully you definitely have a overheating problem. If I remember correctly all those compaq sr series have loud and fast running fans. Computers overheat because of three reasons for the most part: 1) A fan has stopped working. 2) The Thermal Paste on the CPU and Heat Sink has dried up or is not thick enough to keep the unit cool. 3) Dust has clogged the fan vents and inside the computer. Fortunately for you desktops don't have to be completely disassembled like laptops to get to the fan, CPU and heatsink. Just pop the case and you'll see the components attached to the motherboard

Protection mode is there to prevent your receiver from overheating to the point of failure. Try this. Make sure it is ventilated real well. Put it by itself. Don't stack anything on top of it. Even if it has a fan I us a little fan behind my receiver to circulate that warm air off of it. This works real well. Make sure your receiver is setting on a nice hard surface too. Not carpet or anything shaggy like that. Receivers and amplifiers will go into protect if they are rode real hard. Keeping it as cool as you can will minimize this. You can also turn the bass and or gain down on it a bit every now and again to help it cool a little bit. That receiver has final transistors in it that get war as power increases along with the time it is increased. Keep it cool and your it will stay out of protection mode.

get a fan or do a re-stack...open the back of the e-center, Yes it will do a thermal shutdown... just like 3 mile island

do you have sufficient space around the unit? If it is in an enclosed space, has other components on top, etc, you may be overheating the receiver. Once it gets too hot it can potentially cause the issues you mention above.

If you have other components on top, try moving them to another shelf or below the receiver, and if you have a door on an entertainment center, leave the door open to help with air flow.

If the power button binks red after it shuts off it is over heating. Get some air duster and clean out the vents on all sides of the system. Make sure it has plenty of room to "breath" in your entertainment center. In some cases you may have to take it out of the entertainment center to keep the device as cool as possible.

Make sure your filter screens are kept clear.
Protect Components from Overheating
• Don’t block ventilation holes on any of the components. Arrange the components so that air can circulate freely.
• Don’t stack components.
• If you place components in a stand, make sure you allow adequate ventilation.
• If you connect an audio receiver or amplifier, place it on the top shelf so the heated air from it won’t flow around
other components.
Hope this helps!. Otherwise in your owners manual, under troubleshooting it states:
TV turns off while playing
• Sleep Timer, Wake-up Timer, or Watch feature may have been activated. Go to page 45 or 69 for instructions.
• Electronic protection circuit may have been activated because of a power surge. Wait 30 seconds and then turn on again. If this
happens frequently, the voltage in your house may be abnormally high or low.
• The sleep timer may be set.
• Unplug. Wait five minutes. Plug in again.
Hope this help you out.

It is likely that something overheating is causing the problem, but nothing should be overheating. Cleaning won't hurt and may help but it is likely to require repair of the faulty component, perhaps a failing capacitor or amplifier.

You may have a bad protection relay or solder joint at the relay mount position. This relay prevents power supply "thumps" when the unit is first turned on, and also shuts the amp down when there is an overload problem....accordianman