I was working in iDVD last night. I burned the disk, popped it out and played it on my DVD player. Looked good, but the compression was a little lossy. I wanted to see if it played any better on the Mac. So I launched DVD player on the Mac and placed the disk in. When the tray loaded, iDVD was waiting for me to pop in another blank, so once it saw it wasn't blank, it ejected the disk. Realizing that I can't play it while iDVD is still open, I quit iDVD, played the movie, and decided to trim the project and boost the quality. I figured a seconds burn would yield better results. With the tray open and the burned home movie sitting in the tray, I somehow got distracted by something else and forgot to take the disk out. I let iDVD do it's thing, popped in a blank, and hit burn. That's when I almost crapped myself! I forgot to take out the other disk! The sound that came from the Superdrive was horrible. Have you ever heard the sound of two DVDs spinning on top of each other at 500 rpms!? i thought the disks were going to catch fire, or explode, sending plastic shrapnel all over the innards of my new mac pro! I tried to quit iDVD, but it's still trying to read what it thinks is a bank disk. I force quit, still, SuperDrive still spinning, getting louder, more frantic. Now in a panic and not fully understanding why my Superdrive is making this god-awful noise, I pressed the power button in a desperate attempt to halt the SuperDrive. Still nothing, it wasn't working. The SuperDrive was spinning like crazy, making a real nasty noise. My wife comes running into the living room asking me what the hell is going on and that I'm going to wake up the kids! Seriously, it sounded like a Dremel on wood. I held the power button down until the Mac Pro shut off. Woo, that was a close one! I got it to stop. I thought maybe I have a defective SuperDrive; or maybe the DVD blank was defective. I grabbed a paperclip and did that put-a-paperclip-in-the-hole-pop-open-the-drive trick. After the drive popped open, it was then that it hit me! I had left the home movie DVD in the drive and stuck the blank on top of it. What a relief! My Mac wasn't defective, I was just not paying attention. There was no damage to the drive or the blank, but be warned my fellow Mac Pro users! Don't attempt to put 2 DVDs in your SuperDrive at the same time. It's nasty!