I'm using dvd decrypter, and although i set my burn speed to 1x, when burning an iso, dvd decrypter automatically sets the burn spped to 4x. I am using memorex dvd-r's.
If your burner does not have write descripter for a particular speed for that media in its firmware, it cannot write at that speed. Quite honestly I don't think I've seen a 1X descripter for any media I've used in the past 2 years. 2X is usually the slowest. Have you tried 2X and is that reset to 4X by Decrypter as well?
There must be something else going on here. What brand and model of DVD burner do you have? Have you updated the burner's firmware recently? What program did you use to create the iso image file you're attempting to burn? What other DVD burning programs (Nero, etc.) do you have installed? What are the specs for your computer system (processor, memory, etc.)? Does this heppen with every iso file you attempt to burn. Does Decrypter generate any error messages or does it announce a successful burn? Also switch to RW media until the problem is identified and corrected to avoid burning unusable coasters.