Its not disabling dyanamic lights, unless the game is coded in Fixed function T&L, theres noway to know what is a light or not.
When you program a programmable pipeline, you dont enable lights via the API, you basically just code the pipelines to interpret your data you send down as lighting information. Theres noway for the driver to know whats being data is light data and what isn't.
You can use API lights, but most ppl dont bother.
I suspect what is really happening, is nv are shader replacing in the drivers, and losing some high range precision as a result, or the generic shader re-compiler is being a bit too aggressive with its modifications.