white screen?

So I'm not sure if this is the right place to post this, but I'm gonna give it a shot anyhow ;) Some times, when I open the lid on my laptop that is running Calibre, I'm greeted with calibre in fullscreen mode but just a white screen and have to close the app and restart it to get it working properly again. Has anyone else had this happen? Is there a 'fix'? Any help would be greatly appreciated.

Thanks in advance,
Wulfie