I have an old nlited WinXP install. But it's problem is that every time I insert a anything into the USB it asks me that the drivers are not certified and if I am sure I want to install the driver.

I believe the problem has to do with an unsigned USB driver.

What is the fix?

It was an issue with a couple of the older nLites.

I would build it all over again.

the problem is that this machine is already installed. So I have to fix it.

I now I successfully fixed the same issue on another PC but that was 2 years ago.

You can check this or this, not sure it applies.