Windows 7 attendance center informed me about to secure my files from the hard disk.
But the attendance center says, you've to secure your files on an external hard disk or on a network harddisk. Now, I have the problem, that I run Win7 in my VirtualBox, so I can't secure my files on a external hard disk, because the Virtual Box doesn't accept my external hard disk.
I decided to do the network secure, I've only chosen a folder on my normal hard disk and started the secure process and it worked.
This is not a correct solution for securing files but it stops the notification to secure my files.
For the secure process you need some time. The process makes Win7 very slow and sometimes a little bit instable.