Originally Posted by Mr_Mark
Thanks for your reply. I will keep trying as you suggest. But this has been happening for two days now, and each time my computer freezes I have to reboot it. I hope the problem resolves itself soon as I really like Calibre and want to keep using it.
100% CPU is not the same as a Lockup. Just very busy. Let it run a few minutes (longer, if other programs are running like virus scans) the poor thing has a lot of work to do. Forced reboots CAN actually damage open files. Calibre may be updating the metadata in every book folder.