This is a question bred of ignorance, but is it possible that the power draw from both devices is what's setting the power supply off?

(So that the DVD drive takes less power somehow than the hard drive, but plug them both in, and enjoy FAILURECAKES)

I had the same problem to an extent. The computer would shut down entirely out of the blue. I tried starting it up one day and no dice. Nothing came on.

The cause? Fried motherboard. I'd side with that being the problem, from experience. Power supply and MoBo issues sometimes blur together, but the MoBo is the culprit more commonly from what I've seen. I've had a couple MoBo's crash on me in the past, but I've yet to have a power supply go bad.

Heh, for me it's the exact opposite. Even the PoS motherboard I got with my e-machine from Best Buy lasted me without frying, despite my small case and lack of an exhaust fan. The 420w power supply I bought from my friend didn't last a year before literally cooking its guts. (and the backup my friend offered to me turned out to be dead as well.)

Hey guys~

I hate to drag this up, but apparently it WAS the power supply. Pang got some parts overnighted to him for arrival today, and he worked it all out.

You guys are marvellous~ Thanks for all your helps <3

Thank goodness. ^_^
I was really worried, for the reasons that Blah pointed out, that it still might have been the mobo.
Happy to oblige.