Cannot delete file in dashboard

Hi,

When I try to delete the file Leonidas Dashboard.xls in https://bi.3esynaptiq.com/sites/leonidas/Dashboards I get this error: Cannot complete this action.   Please try again later.  Troubleshoot issues with Microsoft Sharepoint Foundation.

I cannot replace the file either. It says that the file is inexistent.  

What can I do to delete this file ?

Thanks

Regards

Joeri Michiels