In each computer of the network, the "subnet mask" in the TCP/IP properties of the network card must be identical.
If one is 255.0.0.0 and the other is 255.255.255.0, they will by design NEVER see each other. Those two settings are common defaults, and they even get "remembered" the same by the human mind...or at least by my mind.
Sigh, I always forget where the TCP/IP stuff is. Can you give me a clue? Thank you very much.
Oh, and about my "problem" searching in XP, just typing it here I had a lightbulb moment and went to the Microsoft website (hadn't thought of searching there) and found out what I have to do. It seems the search function on XP ignores all extensions except the common ones and you have to do some stuff to make it search everything, including, if all else fails, changing the registry. I'll try the simple fix and if that doesn't work, well, I've never had to do anything to the registry and since it isn't my computer I need to search on, I think I'll pass on that one.
Thanks again.