External snow screen

I just woke up macbook from sleep and the external screen appeared to be some kinds of TV snow screen, you know, those from the TV screen when there is no signal It was fun to watch, but concerned me a bit. The macbook screen was fine since 'snow' only appeared on the external screen. The external monitor was returned normal after I switch it off then turned it on again. It is a Samsung 2233BW monitor, and I connect it to macbook and set it as the lower part of the whole display. What could cause this problem? The mac or the external monitor itself?

 

I have a Samsung 2443BW and it does the same thing sometimes, My monitor has a "Source" button, I just hit that and it goes back to normal.

 

Yeah, chances are the monitor was reading from the wrong input. Switching it back to the correct input would solve the problem

 

Where can I find the source button?

 

It should be on the bezel around your monitor's display, or under one of the menu options of your monitor.

 

I found the source option in menu. There are an auto and a manual option for source. The monitor was on auto before and maybe that was the reason it had no signal. Since there is no set up option after manual source option selected, is there anything I can do after switched to manual option to make sure snow doesn't happen again?

 

I just checked that, and set mine to manual. I'm assuming it's probably something you would set on your computer it's self. But I will just leave mine and see what happens.