Error 6256, while loading VSERVER

"The following error occurred whilst loading the device VSERVER. Error 6256:
The server was configured for user-level access control but the Microsoft
Network Security Provider was not found."

The above error occurred following installing a network card in a Win98SE
machine. This machine is networked through a WinXP SP2 machine and has
access to the Internet via ICS. It is not currently possible to browse the
network and see folders and files on either computer from the other.

A third computer (laptop) running WinXP SP1 can use both ICS and browse, and
be browsed by, the WinXP SP2 machine. Only one of either the laptop/Win98
machines are connected to the ICS host at a time.

Upgrading the Win98SE machine is not an option.

What needs to be done to enable the machines to see each other properly so
that files can be transferred as well as using ICS?

Tim