You need to right click on the Command Box ICON and then CLICK on Run as Administrator" in the right click menu. The Command Box will open and you then type in SFC /SCANNOW.
Hope this is the correct forum. Whilst trying to run SFC /SCANNOW on my Inspiron 1525 laptop with Windows XP Sp3 in an attempt to solve a problem with its Reliability & Performance utility, (the subject of my post entitled "Lost Performance Information"  relating to Updating My Score), I keep getting a message telling me that "You must be an administrator running a console session in order to use the sfc utility". I am the owner and sole user and have carried out many functions before, needing administrator status. Can anyone please tell me what I need to do to enable the sfc utility? 
Run As Administrator