Apple Care Tech Tools vs. iMovie vs. blank DVDR

Greetings Mac-Forum!
Until last Sunday, I used to jokingly call myself The Anti-Mac -- didn't like, didn't want, despised most Mac users with their happy little faces... I loved my non-Mac machines all the way back to TRS-DOS. That changed when I brought my 20" iMac home. I have to tell you, eating a couple decades worth of Wintel crow gave me a tummy ache. But the difference my iMac will make in video editing is beyond description.

Impressed as I was with my new alumi-trimmed machine, I managed to kill it on the very first night. I exchanged it at the store the next day, but I'm still wondering how this diaster happened and how to avoid it:

Like the guy at the store told me, I installed the Tech Tools disc in the Apple Care box. It whizzed through the install but never notified me if it was turning on the Auto Shutdown. (This "feature" in Macs is practically unheard of in Windows, so there should some large red warnings, or corrected to not activate when a process is running.)

So, at about 3:30 in the morning I was capturing video from my HDV camera into iMovie when the screen went black. Following the instructions in iDVD (One-Step), there was a blank DVDR in the drive.
The iMac would not turn back on, and I tried about a dozen solutions. Not even the briefest flicker on the screen, nothing. The DVD would not eject either.

* Would having a blank DVDR in the superdrive prevent startup? It never got to the encoding or burning part of the process?
* Does Tech Tools automatically activate Auto Shurdown? (A.S. was not active in the replacement machine, and I've been weary of installing T.T. until I find out more.)
* Will Auto Shutdown interrupt an active, but unattended process like this?

Thanks!
Jeff in Tokyo...

That sounds very odd, and having a blank disc in a drive will not prevent startup. Did you try unplugging the machine (including all firewire devices), waiting a few seconds and plugging it back in? I have a G4 Mac that did something similar. After years and years of service, it refuses to even turn on. Well, it will power up if I let it sit idle for about a day, but if you power it off again for any reason, it needs to wait a day before it will turn back on again.

I've never even heard of auto shutdown, but I know if there were indeed such a feature available, I'd never, ever enable it. I've never used any of Apple's tech tools (other than Disk Utility which is included in the OS), just Alsoft's Disk Warrior which seems to solve minor problems from time to time.