2007WFP goes out of frequency at native resolution/frequency on DVI

I have a Dell 2007WFP connected as a second monitor on a Sapphire ATI 4870 1GB card through DVI, and here lately it will not work once in Windows Visa x64. The monitor will be on with a picture cloning the first on boot, Safe mode and at lower resolutions it looks like but at native 1680x1050 60 Hz it goes black with the amber light on. I can plug the monitor into another computer with a nVidia card and there seems to be no problem running at the native resolution. I have tried and earlier video drivers and clearing the display key info in the registry but I'm thinking this is more on the hardware level. I have not tried reinstalling Windows on this machine but I am not sure if that would help or not.

EnTech Taiwan - Monitor Asset Manager - Info about the monitor

Monitor
  Model name............... DELL 2007WFP
  Manufacturer............. Dell
  Plug and Play ID......... DELA019
  Serial number............ HF73066A0DGL
  Manufacture date......... 2006, ISO week 23
  -------------------------
  EDID revision............ 1.3
  Input signal type........ Digital
  Color bit depth.......... Undefined
  Display type............. RGB color
  Screen size.............. 430 x 270 mm (20.0 in)
  Power management......... Standby, Suspend, Active off/sleep
  Extension blocs.......... None
  -------------------------
  DDC/CI................... Supported
  MCCS revison............. 2.0
  Display technology....... Not supported
  Controller............... Genesis 0x49
  Firmware revision........ 1.2
  Firmware flags........... 0xFFFF
  Active power on time..... Not supported
  Current frequency........ 16742.91kHz, 232.98Hz

Color characteristics
  Default color space...... sRGB
  Display gamma............ 2.20
  Red chromaticity......... Rx 0.640 - Ry 0.330
  Green chromaticity....... Gx 0.300 - Gy 0.600
  Blue chromaticity........ Bx 0.150 - By 0.060
  White point (default).... Wx 0.313 - Wy 0.329
  Additional descriptors... None

Timing characteristics
  Horizontal scan range.... 30-83kHz
  Vertical scan range...... 56-76Hz
  Video bandwidth.......... 140MHz
  CVT standard............. Not supported
  GTF standard............. Not supported
  Additional descriptors... None
  Preferred timing......... Yes
  Native/preferred timing.. 1680x1050p at 60Hz
    Modeline............... "1680x1050" 119.000 1680 1728 1760 1840 1050 1053 1059 1080 +hsync -vsync

Standard timings supported
     720 x  400p at  70Hz - IBM VGA
     640 x  480p at  60Hz - IBM VGA
     640 x  480p at  75Hz - VESA
     800 x  600p at  60Hz - VESA
     800 x  600p at  75Hz - VESA
    1024 x  768p at  60Hz - VESA
    1024 x  768p at  75Hz - VESA
    1280 x 1024p at  75Hz - VESA
    1280 x 1024p at  60Hz - VESA STD
    1152 x  864p at  75Hz - VESA STD

Report information
  Date generated........... 4/7/2009
  Software revision........ 2.30.0.797
  Operating system......... 6.0.6001.2.Service Pack 1

Raw data
  00,FF,FF,FF,FF,FF,FF,00,10,AC,19,A0,4C,47,44,30,17,10,01,03,80,2B,1B,78,EE,EE,91,A3,54,4C,99,26,
  0F,50,54,A5,4B,00,81,80,71,4F,01,01,01,01,01,01,01,01,01,01,01,01,7C,2E,90,A0,60,1A,1E,40,30,20,
  36,00,B2,0E,11,00,00,1A,00,00,00,FF,00,48,46,37,33,30,36,36,41,30,44,47,4C,0A,00,00,00,FC,00,44,
  45,4C,4C,20,32,30,30,37,57,46,50,0A,00,00,00,FD,00,38,4C,1E,53,0E,00,0A,20,20,20,20,20,20,00,73

This is the info the latest Monitor Assist Manager program from EnTech Taiwan says about the monitor. The part I noticed was the line saying Current frequency........ 16742.91kHz, 232.98Hz. I know that's out of the monitors range. At this point I am unsure what I need to do. The monitor has a little bit of warranty left but did not get very far with support from Dell. What can I do next, anybody else have or seen this problem?