Tyan S2390 M.B. locks entering Win98SE

We have had several S2390 mainboards that lock when windows starts up, we have changed EVERY component in system including video, memory,power supply, processor, even mainboards with same result. We have the latest drivers for all installed components. There doesn’t seem to be a problem w/ Asus, DFI, or Abit boards that use the same chipset. Is there a “special” setting I need to change in the registry for Tyan boards?