it is not just a monitor there is PC there,
no PC stated, they work as TEAM. ok.
that being said, 14year old monitors.
no not SAFE but power saver mode,
also called SLEEP MODE to save power losses, (Energy Star and GREEN )
the manual covers this. 9227-AC1 (you missed typing fully this)
'Lenovo ThinkVision L171 9227-AC1 17" LCD Monitor.' AC1 is non USA.
this is very old monitor
and all have this OLD
style internal sleep mode.
covered in the manual.
circa 2005 old.
most this old are dead now from dead CCLF back lamp tubes.
but the manual shows
push menu key on front
then in the OSD MENUS
WE THEN FIND
sleep timer (clock) Inside the monitor,
http://www.manualsdir.com/manuals/165841/lenovo-l171.html
if the PC is silent the monitor goes to sleep.
if the PC goes to sleep
wiggle the mouse or hit space bar until PC wakes up. if sleep is bad in PC turn sleep off.
if PC is dead, then that is wrong.
test the monitor in 2nd PC if monitor works there the monitor is ok, and PC1 is bad.