SCT

I've created a couple image files using ImgBurn. I wanted to use DVD Shrink to compress those files. At first DVD Shrink said there was an error and could not open the files. Then I played around with some check boxes in ImgBurn, burned some more images and then I WAS able to open the files with DVD Shrink. Was the first time it failed just a fluke or is there some important setting that I changed?