In the past you were able to insert references into your Word document using your project and the Citavi Word Add-In. Suddenly you can no longer open the Citavi project from your Word document.
The folder in which Windows saves temporary files is full. The Word Add-In cannot use the folder.
Use the Windows Disk Cleanup feature to empty the folder:
This feature is designed to help you regain hard disk space by removing system files that are no longer necessary to the functioning of the operating system