As a last resort try the following. First back up your network drivers, and your old video bios unzipped onto floppy disks or a Cdr. (you'll have to also put a copy of Nvflash and dos4gw on the same disk with your old bios ROM) Then take your sound card, and network card out, try restarting windows in safe mode. Delete all video, sound, and network drivers. Then flash the bios using instructions from GeForcefaq.com. 

Then restart in regular windows, when it try's to install all the detected new hardware, click cancel. Then go into windows control panel, click system, there will now be several devices under unknown. You should click on your network one. You will know its your network one because one will show up as standard VGA display adapter, the other as a multimedia device, and of course the last one, your network card. 

Now click properties after highlighting your network card. Click reinstall driver, then click show all devices, then click have disk, put in your disk that has the files you recently backed up for it. After installing and restarting windows download the drivers for your GeForce card. Install them, then continue to do the same with your multimedia device. 

NOTE: If this does not work your screwed, you either got a broken *.ROM file or the latest reference bios acted faulty with your system. In order to get your original bios back you have to have a PCI video card, hook it up, load into dos, and try reinstalling your old bios. Then follow the steps previously mentioned of taking things out, and reinstalling drivers.  

Remember, if your card is running fine its unnecessary to flash the BIOS, not always is the latest updated the greatest. (I do not take responsibility for your actions, if you mess things up its not my fault, but feel free to e-mail me, I'm always here to help ^_^.)