I don't see it anywhere on your site, but have you passed (or at least tried) Windows Logo test? That coupled with driver certification kit can show some warnin

I don't see it anywhere on your site, but have you passed (or at least tried) Windows Logo test? That coupled with driver certification kit can show some warnings. It's costly to get signed driver and certified product, but you can just run the tests for free and see if everything is OK.