I purchased copydvd yesterday (310104) and have had nothing but problems, I usually use Clone DVD but a friend suggested Copytodvd package saying it was great.
I am using Windows 98 SE, an Athlon 2500+ (Barton) cpu, 512mb RAM, 60gb hard drive(30gb unused) and an MSI -4a DVD Writer.
I have been through your checklist ie Anti Virus programs running, get the latest version copydvd (2.4.17), make sure the DVD Firmware is at the latest version which it is. (230).
The problems encountered are the PC locking up, cannot see the media (I have two different sources both -R), and rebooting of my PC when it wants to. I have removed the software and I am now able to run CloneDVD and/or Ahead's Nero without a problem.