@dwanthny:
Thanks for your reply.
I know from earlier that the Calibre gets "stuck" at 47% (converting), at 67% (generating mobi) and at 98% (writing file).
Last time (converting from epub) I stopped it at 67% and just over 10 hours. My longest conversion prior to this one is abt 10 minutes.
Anyway, 210m 12s and it has come to 67% now