Why does DVD Decrypter make some image files called IOO files. A few of my images have turned out like this instead of the standard ISO format. I cant burn these IOO files in Nero as it dose not recognise the format. Any ideas on how i can stop DVD decrypter from making IOO files or how i can burn them.

Why on earth are you using Nero to burn them. Simply go into DVD Decrypter and read the disc in ISO mode to the HD and then Select the ISO Write mode and it will write it to the disc. No need to juggle two programs when one will do. If you are talking about doing DVD9s, then simply pick up DVD Shrink (freeware) and then use Nero to burn the VIDEO_TS folder.