I am a new linux user and I'm enjoying its benifits; However, I am having a difficult time with my external monitor. Before my LInux MInt Debian system update, my monitor was working fine. But after I updated my system, my external monitor keeps flickering on and off and returns with the appropriate image. By FLickering on and off i mean, turns black and then conveys the correct picture about 2 secs later. I need some help thank you guys.