Rebooting from a Network Provider? Is it possible?

I work on an authentication product that installs on Win98, NT4, 2K and
XP. It's sole purpose is to obtain user credentials from the user and
authenticate the credentials with the company's ethernet switch. To get
around a problem with the Microsoft IPX stack, a customer has requested
that we have a feature that would reboot the system after the user has
logged off. I've got a solution for NT based OSes however I can't seem
to find the magic solution for Win98. We do provide our own custom
network provider and I've been attempting to force the reboot in our
NPLogoff function however something like ExitWindowsEx does not work.
I've also tried a quick hack that trys the rundll
user.exe,ExitWindowsExec but the result is the same. No reboot occurs.

Does anyone have any possible ideas or solutions?

Thanks,
Dan