How to stop a scan after it has started in 2010

Sometimes I need to stop a scan after it has started.  I can't seem to do it in NAV 2010.  I've looked all over the program, searched here and googled.  Can anyone help me.  Thanks.  I know how to set scans and things like that.  I need to know how to stop a scan when it has already started.   Thanks.  Mac