Welcome to the forum.
As this behavior seems to be independent of the Project, please concentrate on telling us all about your system, from the OS to the version of PrPro, that you are using. The more detail, the better.
Thanks for the reply.
This error occured on Vista when I tried to upload a large volume of files to a project (in hindsight, not a good idea) and the program subsequently stopped responding, which forced me to close the program. Upon restarting, no workspace was visible. After switching to other workspaces, it becme evident what the problem was.The version number is 4.0.0. Is there anything else that would be good to know?
Upgrade to 4.2.2