SHARP HITACHI KEYOCERA, FUJI, SAMSUNG,NEC

I have a computer with an SLI video card (not aware of exact model) and I have a CRT (NEC Multi-Synch FE990)

Today when I tried to boot up, after the BIOS screen and windows load, I get a message saying "Signal Frequency is out of Range -
FH = 49.4
FV = 39.6"

I've tried starting in safe mode and my moniter displays normally, however I don't know what setting to change to fix my problem

I also have attempted a system restore with windows- hasn't worked.

Can anyone help?

The power indicator light that is solid green when the unit is on and functioning properly is now alternating between red and green and the screen is blank. I've been told that this could be the temp sensor, cooling fans, power supply or plasma display failing. Any suggestions would be greatly appreciated. Thanks.

I recently bought a Viewsonic VA800 at a high school fundraiser. The seller swore that it worked. When I plug it in to my computer, the picture goes crazy from the start. The screen resembles an old scrambled cable channel. The menu from the monitor is fine until the desktop loads, so I suspect it is some sort of compatibility issue. The display adapter is a built-in NVIDIA GeForce 6150 LE. My old monitor is a NEC MultiSync E500.