Annoying Onkyo 605 problem.

[X-Ninja]

Hey guys. I bought my Onkyo 605 almost a year ago, and ive dealt with this insanely annoying (what-appears-to-be) "overheating" issue the entire time. Basically, when i turn it up too loud (arount 70) and a bass-ey part kicks in, the receiver shuts itself off and flashes a red light at me.
If anybody knows how to fix this, or any ideas on stopping it from happening, it would be great if you could post them.

At first i thought it was the speaker wiring
- So i bought new speaker cable and re-hooked everything back up

Nothing.

Then i began to think it was my (slightly destroyed) HDMI cable
- So i bought a new one

Nothing.

And now im beginning to think it is because i don't have a sub-woofer. Which may or may not be the issue. ...but before i go shell out however much money it'll cost for a decent subwoofer, it would be nice to know if the problem will remain.

Anybody wanna buy an Onkyo 605!?
...payed 650.00 for this thing, and i got a deal for knowing a guy that works at the place where i got it. Gotta love Canada...

Anyway, Heres a video i made displaying the problem in real time (not that its hard to capture. It happens all the time).