dvdcss_read doesnt update the title key
Basically, if you call dvdcss_read() and that read takes you outside the current title then now you are using the wrong keys;
i was writing a simple program to just read all sectors of the disc and write it to a file, and then the iso file was still encrypted, took me a bit to realize but it was hitting the 'print_error( dvdcss, "no key but found encrypted block" );' error, because i never seeked, i only ever called read() until i got to the end of the disc, and so~ the title key was always \0\0\0\0.