Ok, so I just got my motherboard replaced courtesy of dell after the graphics card burnt out (NVIDIA go 7400). I noticed that the graphics were really laggy, especially when scrolling webpages. Realising that I didn't have the right drivers installed, I DL'd the latest ones from the dell website. Sure enough, problem solved. The machine runs much quicker and scrolls perfectly. Problem solved right?

Unfortunately, no. I restarted the machine after about 5 minutes and the graphics had returned to their old laggy selves. I checked device manager to find the <!> next to the graphics card and the properties console says device failed to start.
I have gone through this process several times, completely uninstalling the card and drivers and starting from scratch, but still to no avail! If I don't shut the computer down after installation it runs fine, but as soon as I shut down, the driver doesn't seem to work next time I start up.

This is doing my head in. Someone help please!