First check that, those files are being used by any program!
If your login is not having administrator rights, it may give that message.
Your login need to have administrator rights.
If your login is having administrator rights, still you get the message, try this...
Right click the folder, choose properties.
Click on the security tab, then on advanced.
Go to the ownership tab and clickedit.
Locate your current account name or type it in and select it.
Check the box to allow this to propagate to all subfolders and containers, then
click apply/ok. It may take some time to run through, but afterwards you
will be able to access the folder and the files in it.