Missing audio files (still in the same folder)

Hi,

for no apparent reason all my project get the same error message “Resolve missing files”. I have not moved or changed the name of the folder with the audio files. They are still there in the same folder. I have used the search function in cubase and located each audio file. But when I enter the project the audio still showes as empty and there is no sound. Only the VST instruments like grooveagent are intact.

Please help me solve this!