Karlof wrote:

Suddenly he is getting the message "The client could not connect
to the remote computer ..." on about 50% of the computers he
tries to connect to.

I take it that all the computers (98 and XP) are on the same local
lan?

On the 98 machine, do this:

Start - Find - Computer

Enter the IP address of one of the unreachable XP machines. If you
don't know what that is, open a DOS prompt on the XP machine and enter
the command "ipconfig". It will most likely be a number like
192.168.x.y, where x will be 0, 1 or 2.

If the computer does not show up in the Find window on the 98 machine,
make sure you can ping it. On the 98 machine, open a DOS prompt and
ping the IP address of the XP machine.

If you can ping, but not see the XP machine in the Find list, then
make sure you are actually sharing something on the XP machine. A
drive or directory for example.