GeForce 7800 GTX Driver Problem

I have been crashing in WoW lately, I think it has to do with my graphics driver, but I can not get the one from Nvidia to install. Everytime I download it, I go to install it and it gets to the same point and says it can not use the file due to it being corrupted.

Using the DirectX Diag tool I have my main driver as nv4_disp.dll.

Any ideas on what I should do?

Check your RAM, probably one stick is failing, run memtest or something to check it.