[ayoshak]

I installed the standard Calibre onto my laptop (Win7), that version refused to open the library on my external hard disk as well.

I tried than to manually interfere with the items in the library, renaming a file (a file without read only limitation). In spite of being the only user of that laptop (and administrator by default) I got the warning that I must confirm the administrator privileges. All it takes is another mouse click, but that is enough to confuse Calibre. I will not rant here about idiocy of Win7 (and Win8) creators.

For you guys with the same or similar problems, go Control Panel, go User Accounts, click onto "Change User Account Control Settings" and drop that slider all the way to the bottom. You will need to restart the PC.


EDIT
There is a better way, see the end of the thread.
END OF EDIT

Ayosha