98 directed_sys_control causes a hangup on unhook

Hi,

I am using 2 drivers one FSFD (File System Filter Driver) and one PND
(Process Notification Driver) in Win98.

Now when we do inter-driver communication using Directed_Sys_Control from
the DDB got from the Get_DDB function, during unhooking the filter and
unloading the PND driver, I am getting a system hang (reboot).

In google I saw some messages a year back that this problem can be solved by
changing a field in the header of the vxds that communicate. When we toggle
that bit in the headers it causes a restore of the bits and thus enabling
the drivers to be unloaded. But it is not happening, it still results in
the system crash.

We need this information on how to unload both the drivers safely. Any
pointer or help is greatly appreciated.

Thanks, Regards,
Vinoj