Unfortunately, there isn't a way to NOT display "signal not found". Televisions aren't typically programmed to "sleep", however, I do see your point of view when using it as a monitor.
At this time, such functionality is unavailable.
Like a hack or something? That's the only thing that bothers me...I'm talking about how a normal monitor sleeps when set to in the OS. I'm using the LN32a650 primarily as a pc monitor and when hooked up via VGA in XP, sleep mode works fine (set to sleep in 20 mins w/ no activity). However, when hooked up via hdmi > dvi (to hdmi2 and renamed to PC) when sleep mode hits it keeps looking for a signal. It'll say 'searching for signal' for a few secs then constantly display 'no signal'. You would think naming it to PC like the manual suggests wouldn't present this..
It doesn't seem to cool down either like when it sleeps via VGA (where it is essentially off) . I work two jobs and also leave the room constantly, so you could understand the convenience of a sleep mode--the inbuilt feature isn't really a solution either.
Is there ANYTHING I can do?