when i turned it on there was no picture, then i unplugged the vga cable from the pc and pops the "no signal" banner, but with no sync , horizontally reduced and with a wining noise from the flyback??. Then i plugged back the vga cable and appeared the windows desktop with no sync ,horiz reduced and wining too. Any ideas. Thanks (p.d. This monitor is new, maybe not even a month of use)