Windows 7 has implemented addition security mechanism to prevent accidental or intentional file or folder modification by not allowing users other then owner of file or folder to access it. Hence incase if you need to access, modify or delete such files or folder you need to take ownership first then assign rights or permission to respective users.
To fix this issue, please follow the next steps
1. Enter to the control panel.
2. Enter to user account.
3. Click in the option "Change User account Control Settings"
4. Decrease to Never notify.
5. Restart the windows and try again.
Now you can access the files without a any permission problem.