I just tried to burn a movie that I made through iDVD to DVD-RW~ The burn was a success but how do you " re-write " over the DVD-RW or erase it?? isn't that what these DVD-RW's are for?? I opened up DISK UTILITY and clicked the QUICK ERASE function but " Optical Erase falied with the error: Whole disk required, slice passed " pops up????? I hope I didn't waste a whole bunch of money on DVD's that can't be re-written on~! I'm using SONY DVD-RW's~