ACL using Windows 7

I am trying to run as command as shown
runas /user:PC2 "notepad mysecret.txt" - this was run as an administrator in the command prompt of Winodws 7.

I expect to see the information as written belowbut this didn't happened.
This runs as PC2, and will probably display the contents and allow edits, since by default often all local users are granted access.

So i went to make change to the permissions by clicking on Edit and then check on given "Full control" access to user PC2.

As soon as i did that and press ok

Error Message : An error occurred while applying security information to
C:\ hiberfil.sys .The processs cannot access the file because it is being used by another process.

There is users PC2 and Administrator PC2 - I went to click on Advance -owner - Edit and tick the box - replace owner and subcontainer and object and press ok
but the above error message still appear .

please can you advice.