Hi I have a computer which i built it has worked fine for months, I had an lg monitor and then it kept going in and out of standby every 2 seconds, i saw the windows screen then the lg screensaver over and over. So I googled possible problems, it said there is a common fault in lg screens that causes this, so I took it back to the shop and got another acer one, I plug this in the pc boots up but the screen does nothing, just says no signal, i checked/replaced the cables, it's not those. but I know it's booting into windows enter password screen, because when i click on where the turn off icon is and hit enter it turns off, I wouldn't know if it booted into desktop because I turned the windows booting sound (da da da da) off ages ago. btw it's vga. ps keyboard light comes on and all sounds are as normal, but can't see anything on the screen.