It's known bug of ClipClip's application. Even the latest 2.1.2045 version has this issue. You can prevent this error by cleaning the latest clips. For the backup purpose, you should save current clips in a safe directory. By default, ClipClip saves clips in C:\Users\username\Document\Clips\Saved Clips
You just need to follow below steps
- Open ClipClip Application
- Click on Edit menu > Clear Latest Clips
So, you will no longer face warning notification on each startup.