I noticed this lately, and it's becoming more often. Basically, when I start my PC, my monitor, which is connected with a DVI-D cable (I don't know what it's called), screen switches to the HD15, where HD15 isn't connected at all. Like, input is changed from DVI-D to HD15, therefore it just blacks out, and then goes back... it's not constant, but it's in random time intervals... I can't do anything on my computer because of this. I even tried connecting it with both DVI-D cable and HD15 cable to the processor, but it still sucks. Is there any way I could force my monitor to stay at only one input method? I'm on XP SP3, and this monitor is about 10 or less years old, a Sony model.
EDIT: also, I think DVI-D is just damaged, and HD15 isn't because whenever it connects to the DVI-D, it shows (sometimes) - no signal, which is not the case with HD15, because when it connects to it, the image stays. Yes, I tried to connect my computer with another monitor, and it worked, so the problem is in my monitor.