by Ken Task.
Before trying again, you might check your apache error logs for something like 'server has gone away' ... that's the DB server and means that max_allowed_packets need to be increased. If apache error logs say something about 'memory allocated exceed' ... blah, blah, blah ... that's a PHP setting for amount of memory a script can consume.
Been my experience, that restores of courses ... especially if they are large *or* heavy processing ... (lot's of quizzes) typically require those tweaks.
'spirit of sharing', Ken