DXdiag problem

Hello, I found this in my dxdiag file:

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DxDiag Notes
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DirectX Files Tab: No problems found.
Display Tab 1: The file nv4_disp.dll is not digitally signed, which means that it has not been tested by Microsoft's Windows Hardware Quality Labs (WHQL). You may be able to get a WHQL logo'd driver from the hardware manufacturer.
Sound Tab 1: No problems found.
Music Tab: No problems found.
Input Tab: No problems found.
Network Tab: No problems found.

What does that mean? Does it need to be fixed? Hope you can help, thank you.

This message just means that your particular version of nVidia's driver software hasn't been tested by the Windows Hardware Quality Lab. Doesn't mean the driver isn't perfectly funtional, or that you must upgrade to a newer driver, WHQL just didn't test your version. Submitting drivers for certification is expensive, and most vendors either don't bother at all, or only submit major driver revisions. You can download newer drivers at:http://nvidia.com/content/drivers/drivers.asp but if the present drivers work OK for you, don't worry, use what you have.

I installed the new ones, and had some issues with graphics in games, and my card is a Ti4600, should I remove these 80xx drivers and go back to an old driver?

I have a Ti4600 and am still using the 78.xx release, because for the older cards like our, newer drivers dont do much by way of improving speeds.