Error reading from file ... xtfugnej.dll

Question of a beginner : I'm tryng to install SQL Server 2008 R2 Enterprise on a Virtual Machine, but I get the following error.

SQL Server 2008 R2 Enterprise setup:

During the Setup Support Files:
Error reading from file D:\1033_ENU_LP\x64\setup\sqlsupport_msi\PFiles\SqlServr\100\Setup\fe72iemr\x64\xtfugnej.dll.
Verify that the file exists and that you can access it.
Click 'Retry' to retry the failed action...

NB : This xtfugnej.dll exists on my DVD but the last folder: 'x64' took more than 3 minutes to open.

What is the problem?

Thanks for any help.