You have tried to burn encrypted files to disc using the Windows CD/DVD Burning Wizard on Windows Vista 64-bit, but it won't work.
Known to apply to the following Sophos product(s) and version(s)
SafeGuard Data Exchange 5.50
Windows Vista 64-bit
What To Do
Burning encrypted files on optical media (CD/DVD) using the Windows built-in burning Wizard is not supported on Windows Vista 64bit. Please use Windows Vista 32-bit or Windows 7 64-bit instead.