If AnyDVD pops up a big dialog about read errors (suggesting a region-free fimware from rpc1.com, cleaning the DVD, etc), and you're using it inside Virtualbox, then the correct solution is:

Stop the virtual machine. The Settings icon will become available. Click it and select Storage. Select the DVD drive, and a checkbox named Passthrough will appear. Enable that and close the dialog. When you restart the guest Windows, AnyDVD will tell you the actual DVD drive's name, model and region, instead of saying it's a region-free vbox DVD drive. It seems AnyDVD is suddenly a lot faster, too.

The other effect of this change is that Windows now has full rights to your DVD drive.