Thanks for the replies so far! Yes, magicjack is similar to Skype in that it is a voip app. But unlike Skype, magic jack uses a USB hadware interface. It looks something like a flash drive but has a USB port and and RJ11 port which allows the user to connect any type of corded or cordless telephone. Also unlike Skype, it is not software based. When you plug it in, the device configures itself (and might download a few files as needed) and voila, instant incoming and outgoing voip complete with a local telephone number.
It uses 2 drive letters, one of which has no effect on DVDfab. The other contains autorun.ini and autorun.exe so basically the device reinstalls itself each time the user reboots. For whatever reason, when DVDfab is launched it locks on the magicjack “drive” and will not unlock no matter how many times you attempt to cancel the “no disc” error message. Until now, my only solution was to either unplug magicjack prior to launching DVDfab or manually configure magicjack as a Windows service (which is a somewhat tedious hack).
Anyway, after posting my original question I discovered what seems to be a workable solution. I installed the free Microsoft “Tweak UI” utility. Using the utility’s file tree, I went to My Computer > AutoPlay > Drives, and deselected the offending magicjack drive in the checklist. So far magicjack and DVDfab seem to be coexisting in peace and both are fully functional. Overall, I think the ability to disable auto scan would be add good functionality to DVDfab but as someone pointed out, the developer isn’t likely to implement it unless more complaints appear. If I run into any further unexpected problems (or find additional solutions) I’ll post them here since the info might benefit others.