win 95 , amd 500 & usb

ok, we have a computer that is running windows 95B with a amd 500 cpu and has usb onboard. The motherboard is a soyo sy-5ssm. We drop the cpu down to 300 load the 350 patch and then bring the cpu back up to 500 then load usb and get a ntkern.dll error on startup. Tried loading the usb drivers then the 350 patch same thing. turn off usb works fine, or if you drop to 300 it works fine. But for some reason at 500 and with the usb the error popups.

Sounds strange, never had any problems as long as the patch is applied after everything else is done at 300. Is it an up-to-date patch? There was an early version from before the 450 came out, which didn't work properly with over 400MHz chips.