When you check in a file to SharePoint using Office 2010 that is encrypted with password protection, you may receive the following error:
Cannot perform this operation. The file is no longer checked out or has been deleted.
By default, when you encrypt a file using password protection, the file properties, or metadata, are also encrypted. When the file properties are encrypted, SharePoint cannot read the existing properties, and therefore cannot write new property values to the document in SharePoint.
To fix this error, try the following steps to disable metadata encryption: