Okay. First, the fact that you have to turn the power off by the switch isn't abnormal. Most modern motherboards are designed to do just that. Normal behavior.

Ok, not having internal USB next to your pwr led, pwr on and reset simplifies things. I'd suggest double checking as I suggest before. Unplug your hard drive, CD/DVD, Video card, etc. Also unplug USB from the motherboard if you have it plugged in. Then try again turning on/off (it probably won't fix anything). If it doesn't fix, unplug your pwr led, reset, and HD led. Double check your pwr on is plugged in right (the cords on my case were actually labeled backwards) and try again. Let us know what happens.

EDIT: Also, the fact that you get absolutely no beeps means we're probably on the right track. Those sounds (called post beeps among other things) don't usually happen if there is a power issue because there is no power to make the beeps (cause the system shuts down like yours).