I just installed a new video card, the I/O magic 32 Mb PCI TNT2, on my system. The driver that I use is the Nvidia Riva TNT2 Model 64/Model 64 Pro. Version 6.3.4.0. The problem is that it does not have a digital signature by Microsoft for some reason I don't understand. I have the Windows 2000 Professional edition, built on Windows NT technology. Now after I installed it, I soon got all of this "stop messages" about drivers or some sort and suggested that I re-install the driver. It also suggested something about disabling the Bios cache or Shadow cache, something like that. So I have no clue. Any explanation or help is greatly appreciated.