I see this is VGA as well as DVI so try the other input. Sorry if I don't tell you how to operate or switch inputs as you've had this for so many years.
I have a Gateway TFT LCD monitor FPD2275W. It working fine except I have this box right in the middle that says NO SIGNAL and under it Red Green and Blue squares. can't move it.
I went to Gateway site and I guess the monitor is too old, they don't show a driver for it. Any suggestions besides get a new monitor?