Most modern Linux distributions come with the automounter enabled. This is normally used to automatically mount newly connected USB stick drives or inserted CD-ROMs. The problem is that this behavior interferes with Syneto's sw-disk and it will fail.

Solution: Disable automount on your distribution. This is how you will disable automount on various Linux distributions: 

FC8:

1. system -> administration -> services: stop autofs and console kit
2. eventually add: service console-kit-daemon stop; service automount stop in sw-disk if on fedora and restart them after writing the disk
3. /etc/init.d/haldaemon stop if service doesn't find console-kit && co

FC9:

1. run ntsysv and uncheck haldaemon
2. service haldaemon stop
3. umount /mnt/disk*

Ubuntu 9.04

There is a solution but you will have to enter your password every time you want to mount a removable device:

1. Press Alt+F2 and enter: polkit-gnome-authorization
2. Go to Storage => Mount file systems from removable drivers
3. Press the "Edit..." button
4. Choose "Active Console: Authentication"
5. Press the "Modify..." button