This is a Windows system installed file with Windows File Protection (WFP) enabled.
sclgntfy.dll has 26 known versions, the most recent one is 5.2.3790.1830 (srv03_sp1_rtm.050324-1447). The average file size is about 20.71 KB.
(Note, the behaviors below are for all versions of sclgntfy.dll, select a unique version for details.)
United States installs about 45.96% of Secondary Logon Service Notification DLL.