one way I have encountered it :
- no cb open
- double click on registered file (eg .cpp)
- cb will open the file BUT in the meantime it shows an error screen saying it can not find the file
most of the time it does not happen anymore, sometimes it pops up again.
Another user wrote (I still have not tried this, shame on me), he can easily reconstruct this when he has the tip of the day active (I have that disabled).