This is interesting... I have been using CloneDVD with AnyDVD for over 1 year with VERY good success (95%+ successful backups).
About a month ago, sometimes (but not all the time), Clone DVD would gave me a Read Error (I don't remember the exact message) at around the 50% - 70% progress mark. It said something like "if error continues, please check the disc and clean it and make sure it is not scratched or damage..."
I check the DVD, and everything is fine, but I would still get the error from time to time (but not all the time).
Then about a week ago, my drive D: failed!!! I turned out that there was nothing wrong with CloneDVD or AnyDVD. My harddrive was physically failing. Those error messages were early warning signs (unfortuately, I ignored them). I always assumed that it was either CloneDVD or AnyDVD causing the error, because I only get the error with CloneDVD.
I have now changed my harddrive and have not encountered any more errors. My old harddrive was only about 4 years old. Since CloneDVD will use ~4.5 GB on your harddrive, it may be stressing your harddrive more than normal. You may not realize you have a bad-sector on your harddrive until you use CloneDVD. Then, naturally, you blame it on CloneDVD.
I see a lot of post about read errors... maybe it is simply caused by a bad-sector on you harddrive! Hope this helps.