I have the latest version of Calibre , 0.647. The last couple of days it have been... unstable.
It started yesterday, when I clicked on the shortcut and got the response: The file cannot be found. I cursed for a bit, but decided to click on the setup file, the setup process offered me the opportunity to repair Calibre. When I clicked on Calibre it worked. Or so I thought.
This morning? The same thing happend. And I have no idea what to now.