Cd base is in use by other user

Hallo I was running the traffic loader and I have this pop up message. Kindly assist on how to get rid of it because if i press cancel the program stops. It takes about 13000 seconds to calculate this step.

right mouse click on .cbd file → SOFiSTiK → Clean Locks

Thank you so much however i had to go and delete a cdi file insterad because even after cleaning locks it did not work but once i deleted the cdi file and ran the program afresh it no longer had this problem.