Win 7 won't recognize my monitor

What type of connection are you using?

digital, DVI dual output card, NVIDIA GeForce 7900GS.

any one?

WHen you say suddenly, you mean that up to now windows recognized the monitor as "vg2230wm LCD monitor" and now it doesn't? Monitors have some drivers too, so that Windows can recognize their specs and color profiles properly, so try reinstalling your monitor drivers. You probably got a cd when you bought it, or you could try Viewsonic's site.

I didn't check if win 7 recognize the monitor before. But it can show 1680x1050 native resolution. But one day win 7 suddenly can only show 10245x768 max as non-pnp mointor. I tried to install viewsonic signed driver, but it reported as monitor not found.
I found out last night that when machine boot up with 2 monitors (1 viewsonic vg2230wm and 1 LG L226WT), then swap cables, win 7 can show higher resolution choice for vg2230wm while not losing LG resolution. But that means I have to swap cable every time machine boot up.

I don't have the CD when I bought it used. I tried viewsonic signed win 7 32-bit driver and it reported error not finding my monitor at the end of installation.
updated: I tried unsigned driver from viewsonic, it ends with same error. I think win 7 didn't recognize the monitor. i came cross some thread saying maybe my video card is giving up, one port at a time. I guess I need to wait till it's totally given up before shelling out 100+ bucks for a new card. I'm at my wit's end now.

Thanks yxd0018 I have been searching for a solution all night.
I didn't think it would matter to actually take the cable out but it did it.
Thank you

glad it helped.